After Senate candidates made last-ditch efforts to persuade voters through TV ads, Tuesday's election will determine control of the chamber and eight races are particularly contentious.
Each party controls 50 seats in the Senate, so the majority is determined by Democratic Vice President Kamala Harris' tie-breaking vote. Democrats are trying to defend their incumbents and possibly pick up a seat or two.
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Analysts initially projected a blowout victory for Republicans across the board in the face of low approval ratings for Biden and voter concerns about the economy and inflation.
But the Supreme Court's decision overturning Roe v. Wade, a series of legislative wins for Democrats on Capitol Hill, and primary victories by GOP candidates endorsed by former President Donald Trump in battleground states gave Democrats momentum.
Those tailwinds abated as inflation remains a top concern for voters. And several races that seemed like a guaranteed win for either party have tightened up over the months since the primaries, turning some races into toss ups, according to John Sides, a political science professor at Vanderbilt University.
“Races that appeared more lopsided are tightening. Republican candidates who were lagging (are) pulling closer, which is more in line with what the overall partisanship of those states and districts is, but also just what the fundamental of the election are, which is not an easy midterm environment for the Democratic Party – that hasn’t changed,” Sides told USA TODAY.
Despite the historical challenge for Democrats during the midterms, the narrow partisan divide across the country is among the challenges facing both parties, Sides added.
“We kind of live on a knife’s edge with regard to who controls the government,” he said.
Here are eight important Senate races to keep an eye on:
In Nevada, Laxalt gains ground with voters with focus on the economy
A USA TODAY/Suffolk poll of Nevada voters released Oct. 12 showed the GOP Senate race a statistical tie. GOP challenger Adam Laxalt was closing in after trailing by seven percentage points in the USA TODAY Network's August survey.
Sen. Catherine Cortez Masto, the most vulnerable Democrat candidate in the Nov. 8 election, led Laxalt by 2 percentage points, 46%-44%, the poll found, after her opponent gained ground with Hispanic voters through his economic messaging.
Laxalt is among many Republican candidates gaining ground with their emphasis on the economy.
Inflation and the economy remained the top issues among Nevadans with 43% of likely voters naming it their main concern, the poll found. Only 25% of voters named abortion at the top. But there was good news for Cortez Masto: asked about the impact abortion would have choosing a candidate, 40% of those surveyed rated the issue a 10 out of 10.
In addition, Laxalt has been trying to walk back past comments supporting restrictions on abortion access.
Laxalt has declared abortion access as "settled law" in Nevada after a 1990 referendum. Republican Senate nominee also declared that the state would remain pro-choice in a USA TODAY Network op-ed column.
In Pennsylvania, Oz tightens the race while Fetterman battles back from stroke
Lt. Gov. John Fetterman's bid as the Democratic nominee for the open Pennsylvania Senate seat left empty by Republican Pat Toomey's retirement was seen as the best chance for his party to keep – and possibly grow – the slim majority. But GOP nominee Dr. Mehmet Oz has surged after a rocky debate performance by Fetterman.
Fetterman's nearly double-digit lead over his opponent during the summer has turned into a contest that's up for grabs, according to a USA TODAY/Suffolk poll conducted Oct. 27-30. Fetterman is at 47% and Oz is at 45%.
Oz, a caridothoracic surgeon, struggled during the Pennsylvania primary, being painted as an out-of-touch Hollywood outsider from New Jersey. However, the race for the state's Senate seat turned competitive after a barrage of attacks on Fetterman’s crime record and personal health following a stroke he suffered earlier this year.
It's not clear whether Fetterman's debate performance – where his speech was halting at times and his answers were sometimes confusing – will hurt his standing among voters in a race he's led consistently.
How Oz closed the gap: Is it a warning sign for Democrats?
Fetterman suffered the stroke days before the state's May primary, causing the former Braddock mayor to take months off from the campaign to recover.
“If you can’t get people to like you, get them to dislike your opponent,” said David Paleologos, director of the Suffolk Political Research Center. “This is a textbook strategy of Oz driving up his opponent’s unfavorability to make the race closer.”
The GOP spent millions on TV ads to portray Fetterman as soft-on-crime, highlighting the Democrat’s past clemency efforts and his progressive views on criminal justice reform.
Oz-Fetterman debate: 5 takeaways from Pennsylvania's John Fetterman-Dr. Oz debate in key U.S. Senate race
A closer look at Pennsylvania: At rally for Fetterman in Pennsylvania - and beyond - abortion takes center stage
In Georgia, Warnock lead slim despite Walker's missteps
In Georgia, Democratic Sen. Raphael Warnock and Republican Herschel Walker faced off in a contentious debate Oct. 14, the only one before the Nov. 8 election. The candidates exchanged attacks over pressing issues, including inflation, nuclear weapons and an abortion scandal.
Both candidates were on defense during the debate as Walker called recent allegations that the former NFL running back paid for an ex-girlfriend’s abortion a “flat-out lie,” while Warnock dismissed Walker’s attempts to paint the Democrat as a lackey for Biden, whose approval rating is low among Georgians.
Georgia Senate race: Warnock needs his 2020 coalition. But inflation, fatigue could keep them home
While previous surveys showed the race tied, recent polling have found Walker dragging slightly behind his opponent, suggesting he lost some support of Georgians after the reports that he paid for an abortion in 2009 and later urged the same woman to have another abortion, according to The Daily Beast and New York Times.
Walker has been clear on his anti-abortion stance, voicing support for a proposed federal 15-week abortion ban with no expectations for rape or incest.
Warnock, who is seeking reelection for a full six-year term after winning his Senate seat in a special election in 2020, was in a dead heat with Walker by Thursday, according to an average of polls by FiveThirtyEight.com.
Warnock has personal issues of his own to face in his attempt to keep his seat and Democrats control of the Senate. Along with Biden’s low approval ratings, the senator must also overcome sky-rocketing inflation and fears of a recession to win Georgia a second time.
In Arizona, Kelly, Masters clash over immigration, abortion
Sen. Mark Kelly, D-Ariz., and Trump-backed venture capitalist Blake Masters are vying for the Arizona Senate seat.
The candidates went head-to-head in an Oct. 6 debate, the only scheduled one before election night, where they clashed over issues of immigration, abortion rights and election integrity.
Kelly went on defense as Masters worked to paint the incumbent as an accomplice to Biden’s agenda, attempting to tie the Democrat to the administration’s increased spending and southern border strategy. Kelly disputed the Republican’s attacks, saying he only supported Biden some of the time and pushes back against the administration when he disagrees, including on how to secure the southern border.
The senator, seeking to win reelection to serve a full six-year term, accused Masters of changing his views on what abortion restrictions he’d support to win the election.
A poll released Friday by Emerson College Polling has Masters with a razor-thin lead over Kelly, 48% to 47% with a 3-point magin of error, The Hill reported. About 1% of voters are undecided, essentially leaving the race in a tie.
The economy/inflation, abortion and immigration were the issues Arizona voters cited as their top issues as the midterm elections approach, the poll found.
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In New Hampshire, unpopular Hassan leads far-right challenger Bolduc
Democratic Sen. Maggie Hassan led Republican nominee Don Bolduc, a Trump supporter, in New Hampshire but her advantage narrowed as the election drew near.
Support for the incumbent fell within the margin of error, according to an Emerson College Polling/WHDH 7 News survey conducted October 18-19.
Hassan had a difficult start to the general election season as a St. Anselm College poll found her at a 44% approval rating among New Hampshire voters.
Bolduc, a retired Army general know for his controversial statements and fervent support of Donald Trump, has been shunned by the New Hampshire GOP establishment because of his far-right stances.
Tom Rath, a former National Republican Committee member and advisor to many GOP presidential candidates, called Bolduc a "lone wolf," noting that he lacks the backing of any notable Republican or organization.
Bolduc has publicly supported a series of far-right statements that Republicans are concerned won't work well with the moderate voters necessary to win Hassan's seat, including insisting that Trump won the 2020 election over Biden and suggesting the FBI should be abolished.
The state's Republican Gov. Chris Sununu has been clear with his dislike of Bolduc, endorsing his opponent during the primaries and calling Bolduc a "conspiracy-theorist-type candidate."
In Wisconsin, Johnson leads Barnes
GOP Sen. Ron Johnson, R-Wis., and Democratic Lt. Gov. Mandela Barnes face off in the high-stakes race in Wisconsin and a chance for Democrats to pick up a seat.
The pivotal race has remained close throughout the election season as the candidates remain within the margin of error in polling. However, Johnson, the most vulnerable GOP incumbent, surged to a 6-point lead among likely voters, 52% to 46%, according to an early October Marquette University Law School poll. When the poll was taken again a week before Election Day, Johnson was up 50% to 48%, among likely voters.
The candidates went head-to-head in two scheduled debates, where they sparred over crime, abortion and the Jan. 6 insurrection at the U.S. Capitol. Both went on offense during the second and final debate, just three weeks before the midterm elections.
Johnson, who walked back his self-imposed term limit of 12 years in office to run for his third-term, attempted to tie Barnes to the Defund the Police movement. Barnes countered by pointing to the law enforcement officers present at the Jan. 6 insurrection while referring to Johnson's efforts to downplay the day's events.
Barnes, who would vying to be the state's first Black senator touted his support for abortion access, declaring that in Johnson's "America, women won't get to make the best choice for their health." Johnson responded with his continued pitch for a referendum on abortion, allowing Wisconsin voters to decide the issue.
Former President Barack Obama headlined a rally on Oct. 29 in an effort to boost Democrats, including Barnes and Wisconsin Gov. Tony Evers, who is seeking reelection.
In NC, a red Senate seat that's competitive
The race for North Carolina's empty Senate seat left open by the retirement of Republican Sen. Richard Burr didn't start as a must-watch. But the battle between GOP Rep. Ted Budd, R-N.C., and former state Supreme Court Chief Justice Cheri Beasley, a Democrat, is drawing a national spotlight.
Polling shows Beasley and Budd practically neck-in-neck, with Budd just barely beginning to edge out his Democratic opponent.
A mid-October Civitas Poll showed Budd over Beasley by fewer than 4 points: 46.9%-43.1%.
The candidates faced off during an Oct. 7 debate, clashing over a range of issues, including abortion, crime and cannabis while sprinkling in person attack against each other.
Budd would not say whether he supports a national abortion ban, whether he wants Trump to run in 2024 or whether Biden won the 2020 election and is the legitimate president. The Trump-backed candidate was among the 147 GOP members of Congress who refused to certify the 2020 presidential election results, a decision he continues to stand by.
Debate takeaways: North Carolina Senate candidates joust on abortion, marijuana and 2024
When asked, twice, if she'd join Biden on stage if he were to campaign in North Carolina, Beasley downplayed the possibility, possibly to distance herself from the president. Biden has low The president had a 34% approval rating in the state, according to a High Point University poll.
Beasley was pressed on crime by her opponent, denying his claims that she's in support of defunding the police and saying the country needs to invest in community-based violence prevention programs.
Beasley has significantly outraised Budd – by more than double. But North Carolina has not sent a Democratic senator to Washington since 2008.
Trump has visited the Tar Heel State to stump for North Carolina Republicans, including Budd.
In Ohio, Trump-backed Vance leads Ryan by slim margin
In a nail-biter, Republican J.D. Vance has a razor thin lead over Rep. Tim Ryan, D-Ohio, in their race to succeed retiring Republican Rob Portman.
Vance and Ryan were within the margin of error, 47% to 45%, according to a USA TODAY/Suffolk University poll in October.
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While Vance touted his support from Trump, Ryan distanced himself from Biden as the president's approval rating in the Buckeye state hovers around 39%.
The Senate candidates faced off in two debates before Election Day, sparring over abortion, guns, immigration, the economy and inflation. The poll found the economy and inflation to be the issue at the top of Ohioans' minds, followed by abortion and threats to democracy.
Vance attacked Ryan for supporting federal spending bills, including the $1.9 trillion American Rescue Plan, and attempted to cast Ryan as a "career politician," reminding voters of Ryan's 20-year tenure in Congress.
Ryan countered saying that the infrastructure package and CHIPS Act he supported will bring jobs to Ohio and that he has disagreed with Democratic leaders from time to time. The Democrat took a shot at his opponent, accusing Vance of pushing the great replacement theory, a conspiracy that argues non-white people are brought to the U.S. to replace white people.
This article originally appeared on USA TODAY: Eight midterm election races to watch as Senate majority at stake