Labour MPs have criticised Sir Keir Starmer’s decision to welcome Tory defector Natalie Elphicke, the second MP to cross the floor in two weeks.

Ms Elphicke quit the Conservatives just moments before Prime Minister’s Questions on Wednesday, hitting out at Rishi Sunak’s “tired and chaotic government” and accusing the Prime Minister of failing to deliver on his promise to “stop the boats”.

But her debut as a Labour MP has not been welcomed by all of her new colleagues, with some raising concerns about comments she made after her then-husband was convicted of sexual assault.

One Labour MP told the PA news agency: “I think it’s utterly disgraceful.

“She’s totally right-wing and supported her husband when he sexually assaulted women.

“There are Labour MPs still suspended and we’re welcoming MPs who have voted to push people into poverty. I despair.”

Another MP said she had been left in tears by the news of Ms Elphicke’s defection.

Ms Elphicke’s former husband and predecessor as MP for Dover, Charlie Elphicke, was convicted in 2020 of sexually assaulting two women and sentenced to two years in prison.

Although she ended the marriage after his conviction, Ms Elphicke supported his unsuccessful appeal and described the verdict as “a terrible miscarriage of justice”, saying Elphicke had been “attractive, and attracted to women” and “an easy target for dirty politics and false allegations”.

She was subsequently suspended from the Commons for one day alongside two other MPs after trying to influence a judge who was deciding whether to release character references they had written for Elphicke.

Jess Phillips, the former shadow minister for domestic violence and safeguarding, said Ms Elphicke should “account for her actions”.

She told ITV’s Peston: “I’m all for forgiveness but I do think that that needs some explaining.”

The branch of the GMB union that represents MPs’ staff said it had requested a meeting with Labour whips “regarding vetting of sitting MPs and candidates”, with branch chairwoman Jenny Symmons describing the decision as “really, really poor and disappointing”.

A Labour Party spokesman told reporters on Wednesday that the matter had been “dealt with previously”.

He said: “Natalie can speak to her own remarks on that and she has spoken extensively about that case, and I don’t have anything to add to what she has said on that subject.”

Other Labour MPs raised concerns about Ms Elphicke’s political opinions, with one saying that while they thought she had done “really good work” on housing policy, her other views were on the “hard right”.

Another backbencher told PA the decision provided little comfort for those questioning Sir Keir Starmer’s political judgment and showed “cack-handed party management skills”.

They said: “They didn’t need to do this. Now they have a new Labour MP who, unless kept in a sealed room, will be a hostage to fortune between now and the general election. Everything she says and writes will be scrutinised in detail.

“Did they really need to do this? The answer is clearly no. Ultimately, if this is the quality of their political decision-making, 20 points ahead and in opposition, then it’s not looking good when they’re in government and under pressure.”

Ms Elphicke said the “key deciding factors” in her defection were housing issues and “the safety and security of our borders”.

Speaking to reporters in Sir Keir’s parliamentary office after Prime Minister’s Questions, she said: “In 2019, the Conservatives stood on a manifesto that was very much centre ground, but under Rishi Sunak they’ve abandoned the centre ground and broken many election promises.

“Meanwhile, under Keir Starmer, Labour have changed. And I think that change is going to bring a much better future for our country, and that’s why I was so keen to join the Labour Party and play my part in bringing that important future forward.”

A year ago, Ms Elphicke used a newspaper column to claim “not only have Labour got no plan of their own to tackle illegal immigration, they simply do not want to” and said Sir Keir “has pledged to rip up our world-leading partnership to remove illegal migrants to Rwanda”.

Asked about her previous criticism of Labour over immigration policy, she said Mr Sunak “was the man who said he would stop the boats” but so far this year there had been “record numbers of small boats arrivals”.

“So he’s not stopping the boats and he’s letting the country down.

“Meanwhile under Labour, they are clear that it is important to have defence and they want to make sure that they have good national security. So I think we should have confidence that Labour are the party who will tackle this issue of the small boats crossings.”

Ms Elphicke is standing down at the general election, with former soldier Mike Tapp remaining Labour’s candidate for her seat, renamed Dover and Deal in the boundary changes coming into effect at the general election.

Ms Elphicke denied that she had been offered a peerage by Labour, but aides suggested she could take on an unpaid role working on housing policy.

Despite the backlash, the defection was still another blow for the Prime Minister, after MP Dan Poulter’s decision to leave the Tories for Labour in April and the dismal local election results for the Conservatives last week.

At Prime Minister’s Questions, Sir Keir Starmer asked Mr Sunak “what is the point of this failed Government staggering on” when “the Tory MP for Dover on the front line of small boats crisis says the Prime Minister cannot be trusted with our borders and joins Labour?”

Cabinet minister Michelle Donelan told Sky News she was “gobsmacked” by the defection, adding it was “nonsensical”.

She said: “I think there’s bigger questions about her judgment here and this speaks more volumes for her decision-making than it does the Government’s plan.”

A Conservative member of Dover District Council described the defection as a “kick in the guts”.

Stephen Manion, who represents Eastry Rural, said he was “sickened” by Ms Elphicke’s decision to cross the floor.

Downing Street said Mr Sunak would not change course over his immigration policies in the wake of the Dover MP’s defection.

The Prime Minister’s press secretary brushed off questions on whether Mr Sunak is concerned about the second defection in recent weeks, saying he is focused on “the priorities of the British people”.

The press secretary said she hoped Ms Elphicke would explain why she changed her mind after being “very forthright in attacking ‘Sir Softie’ Starmer” and “Labour’s open-borders policy”.

SNP Westminster leader Stephen Flynn highlighted a social media post from Ms Elphicke urging Tory members to vote for Liz Truss during the 2022 leadership campaign.

“Meet Natalie, the new Labour MP,” he said. “What does this say to their values?”