Labour members were in open revolt against trade union-backed reforms to the party on Sunday, with many expressing anger on the conference floor about watered-down proposals for reforming MP selections and leadership contests.

The controversial rule changes, proposed by Labour’s ruling national executive committee (NEC), would make it considerably easier for local members to deselect their sitting MP by reforming the so-called trigger ballot system.

However, they do not go as far as mandatory reselection, which many members had wanted.

Trade unions also backed reforms to Labour leadership contests that were opposed by many rank-and-file members who argued they gave members even less of a say than the existing system.

At the beginning of the debate in Liverpool on Sunday, a small but vocal crowd of party members booed and shouted “shame on the unions” after the conference voted narrowly to accept the conference timetable – a vote that acted as a proxy for dissatisfaction with the democracy review.

One party source estimated 90% of members had voted against the conference report but 90% of trade union delegates were in favour to ensure the report passed despite the dissatisfaction. The final result of the conference vote on the individual rule changes will not be announced until Monday.

The reaction from members on the conference floor sparked an angry response from some senior trade union staff. Sarah Owen, the GMB political officer, tweeted: “To the people shouting ‘shame on the unions’ they have no idea of the importance and strength of the bond between the Trade Union movement and the Labour Party.”

To the people shouting “shame on the unions” they have no idea of the importance and strength of the bond between the Trade Union movement and the Labour Party. #Lab18 — Sarah Owen (@SarahOwen_) September 23, 2018

Unite’s general secretary, Len McCluskey, told a fringe meeting he was concerned over the splits that have emerged around mandatory reselection and urged members to follow the compromise because it has been put forward by Labour’s leader.

“I was slightly shocked to see such a divide between constituency delegates and union delegates,” he said. “What comrades need to understand is that Jeremy Corbyn is asking us to accept this alternative.”

Unison’s president, Gordon McKay, sounded a warning about any division. “The trade union movement was there at the birth of our party – we haven’t come in the last few years,” he told the conference. “I’m surprised some people are saying the unions should have no say in election of our leader or be able to hold our MPs to account.”

Jeremy Corbyn and Tom Watson at the Labour conference. Photograph: David Gadd/Sportsphoto Ltd./Allstar

Matt Wrack, the general secretary of the FBU, one of the few unions to vote with the rest of the membership, said there was “an unhealthy division between the union delegates and the membership” that needed to be addressed.

One of the most controversial measures is reform to the election of the next Labour leader. Currently, any MP must get the backing of 10% of their fellow MPs before they can stand for leader, but many members wanted that reduced to 5%.

Instead, after unions backed a compromise, the threshold will stay at 10% of MPs, but a contender must also win the backing of 5% of local parties or 5% of trade union affiliate members, in effect the backing of two big unions.

Several delegates spoke passionately against changes to the leadership contests, arguing it would make it harder for candidates to get on the ballot.

Brentwood and Ongar party member John Pickard called the proposals “a dog’s dinner” and urged the trade unions to “look at the mood and feeling” within the constituency parties. Delegate Pete Firmin from Hampstead and Kilburn called the changes “a step backwards from what we achieved last year”.

Another change will make it easier for local members to force a full selection process for their MPs. Currently, 50% of local branches and affiliates, such as trade union branches, must express dissatisfaction to force a contest against a sitting MP.

A delegate at the Labour party conference. Photograph: Leon Neal/Getty Images

Under the new rules, that figure will be reduced to one third of branches or affiliates, although they do not go as far as Momentum’s bid for full open selections to be held in every seat automatically.

The leftwing grassroots group has urged delegates to oppose the changes to the leadership threshold but has said delegates should back the trigger ballot reform at the risk of having no change at all.

However, despite Momentum’s advice, many delegates in the conference hall urged members to vote down the party’s proposed leadership reform in the hope of forcing a vote on mandatory reselection.

Steve Arloff, the delegate from Bradford West, said sitting MPs expected “a job for life” and that hundreds of thousands of members wanted reform. “Many sitting MPs who have lost the respect and confidence of local parties cling on to their positions in parliament with scant regard for the people who work their socks off to put them there,” he told the conference.

Ian Lavery, the party chair, said changes would require “compromise and patience in abundance”, a hint at the unhappiness of many members on the conference floor.

Other changes include adding a second, female deputy leader of the Labour party to sit alongside Tom Watson, creating a disability representative for the NEC, and proposals to increase black and ethnic minority representation.