I went to work for Keir Starmer because he promised to unite the party. I regret it now

Keir Starmer would not have been elected as Labour leader if he had suggested publicly or privately that he intended to re-establish weighted votes for MPs in leadership elections, taking power away from regular members and ensuring future leadership contests would be less inclusive than the one he himself won. Labour party members would not have voted to abrogate their own rights. The triumphalism of some on the party’s right following the changes to the party’s rulebook will be greeted with resentment by thousands of party members.

Briefings from allies of the leadership say that the reforms show Labour has changed, drawing a line under the Jeremy Corbyn years and focusing outward. Instead, they have shown that Labour hasn’t changed at all – it is still focused on internal fights. Until someone decides to take a lead to stop the cycle of open strife, the party will struggle to win a general election.

Related: Labour conference: Corbyn says Starmer ‘wants to prop up, not challenge, wealth and power’ – live

It should be obvious to any sober observer that a few changes to Labour’s leadership rules are not going to benefit the party by electrifying swing voters in marginal seats or mobilising supporters in its strongholds. But the cost paid on the other side of the equation in infighting, squabbling and deepening mutual suspicion will be heavy.

Last week, Keir Starmer told Labour’s shadow cabinet that he wanted a return to the electoral college, a system introduced some 40 years ago but then abolished by Ed Miliband in 2014, which gives MPs’ votes the same weight as hundreds of thousands of members combined. Many experienced Labour politicians knew immediately this strategy would not succeed. They were right.

Although it was claimed that the reforms would enhance trade union influence, they were poorly received at a meeting of Labour’s affiliated unions last Wednesday and were dropped by Friday. Then new proposals came forward, increasing the number of nominations candidates must secure from MPs from 10% to 20% of the parliamentary party.

Of the candidates who stood for the Labour leadership in 2010, only David and Ed Miliband would have met the new threshold to be a candidate. Ed Balls, Diane Abbott and Andy Burnham would not have made the ballot. In 2015, only Andy Burnham and Yvette Cooper passed this new quota. No Liz Kendall. No Jeremy Corbyn, the eventual winner. Most strikingly, in 2020 Keir Starmer alone met the criteria.

Of course, members of parliament would have nominated differently under such constraints – but not in a good way. Under the new scheme, deal-making in private before a final shortlist emerges will become much more important than open debate in the country. Whichever way you look at it, it is designed to reduce the range of candidates open for unions and members to eventually decide between, narrowing their choices considerably before a single vote is cast.

The dispute has overshadowed Labour’s first conference since the pandemic struck. Shadow cabinet members Andy McDonald and Angela Rayner kicked off conference by launching a set of policies for working people that the party could unite around, but more attention was on the fight over the rulebook. McDonald has now resigned from the shadow cabinet, stating that Keir Starmer has made Labour “more divided than ever”. Likewise, Ed Miliband set out a powerful agenda on climate change but his speech was obscured by these other dramas. It looks bad, and responsibility for these presentational choices lies with the party leadership.

Related: Angela Rayner angered by Andy McDonald’s resignation

During his leadership election, Starmer sold himself as the unity candidate and said the party would not “oversteer” from many of the best elements of the Corbyn era. “We are not going to trash the last Labour government … nor are we going to trash the last four years”, was the line, and the 2017 manifesto was to be treated as a “foundational” document.

These promises were backed by the extending of an olive branch to the left. So when I was approached to join Starmer’s campaign after working for left campaigns and politicians including Jeremy Corbyn, I saw the commitment to policies I strongly support as clear common ground between the two eras.

Unfortunately, the shortfall between what was promised and what has happened since raises some very big questions for thousands on the left and soft left who voted for Starmer to be leader.

It is very hard for me to say this because in politics people aren’t supposed to admit they got something wrong. But while the unifying pitch that Starmer put to the membership was open, conciliatory and correct – and explains the big vote he secured – it has not been delivered. It sadly proved to be the wrong thing, for me at least, to have supported that leadership campaign. From my own perspective it was a mistake and ultimately a political dead end. Starmer’s leadership constructed an alliance and then unravelled it. You cannot promise unity then deliberately pick fights and expect people to say that is OK. It’s not.

There is plenty of good work being done by people at all levels of the Labour party: great metro mayors, the leadership of Wales, councillors, fantastic forward-thinking trade unionists, activists, members, organisers, shadow cabinet members. An effective, modern left is more likely to emerge from that than from old playbooks at the party conference.

• Simon Fletcher is a former adviser to Keir Starmer, Jeremy Corbyn and Ed Miliband