British Prime Minister Rishi Sunak was accused Wednesday of leading a "chaotic" government as another one of his Conservative lawmakers defected to the main opposition Labour Party ahead of a looming general election.

In a stunning move just ahead of weekly prime minister's questions, Natalie Elphicke crossed the floor of the House of Commons to join the ranks of Keir Starmer's Labour Party, which appears headed for power after 14 years.

"We need to move on from the broken promises of Rishi Sunak’s tired and chaotic government," said Elphicke, who represents the constituency of Dover in southern England which is at the front line of migrant crossings from France. "Under Rishi Sunak, the Conservatives have become a byword for incompetence and division."

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Elphicke is the second Conservative lawmaker to defect to Labour in two weeks after Dan Poulter quit in anger over the government’s handling of the National Health Service.

The defection of Elphicke is particularly surprising as she was widely considered to be on the right of the Conservative Party and has been hugely critical of Labour in the past. But she has recently been increasingly disapproving of the government's approach to migrant crossings.

former Conservative MP Natalie Elphicke

Former Conservative MP Natalie Elphicke, right, speaks with Labour leader Keir Starmer, in his parliamentary office in the House of Commons, London, on May 8, 2024. Elphicke recently switched from the Conservative Party to the Labour Party. (Stefan Rousseau/PA via AP)

"From small boats to biosecurity, Rishi Sunak’s government is failing to keep our borders safe and secure," she said.

Just under 30,000 people have arrived in Britain in small boats in 2023, and Sunak has made reducing that number a key issue ahead of the election due this year, notably with his controversial plan to send some asylum-seekers to Rwanda. More than 8,000 have made the dangerous crossing already this year.

Elphicke was elected in 2019, taking over the Dover seat that had been held by her then-husband Charlie, who was jailed for two years after being found guilty in 2020 of sexually assaulting two women.

Starmer welcomed Elphicke to the Labour benches as well as Chris Webb, the party's new lawmaker in Blackpool South in northwest England following his big victory in a special election last Thursday.

Starmer reiterated his call for Sunak to call a general election now, saying the Conservatives cannot carry on when even a lawmaker at the forefront of the small boats crisis said Sunak "cannot be trusted with our borders."

Last week, the Conservatives suffered a historic drubbing in local elections, losing nearly half of its candidates, while Labour made gains and won most of the key mayoral races it fought, including in London.

Particularly encouraging for Labour was that it won in areas that voted for Britain’s departure from the European Union in 2016, and where it was crushed by former Prime Minister Boris Johnson at the general election in 2019.

Elphicke's defection may help Labour deflect Conservative attacks during the election that it may seek to reverse Brexit. In her statement Wednesday, she said Labour "has accepted Brexit and its economic policies."

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Her defection has not only raised eyebrows within the Conservative Party.

The left-wing Labour grouping, Momentum, said Elphicke has "consistently demonized refugees and aid groups" and that she "should have no place in a Labour Party committed to progressive values and working-class people."

In the U.K., the date of the general election rests in the hands of the prime minister. It has to take place by January, and Sunak has repeatedly said that his "working assumption" was that it would take place in the second half of 2024.