A Conservative MP defected to Labour on Wednesday in a fresh blow to Rishi Sunak.
Dover MP Natalie Elphicke said the Prime Minister and Tory government “cannot be trusted” to “keep our borders secure”.
Under the PM’s leadership, the Conservative party has become a “byword for incompetence and division”, she added. “From small boats to biosecurity, Rishi Sunak’s government is failing to keep our borders safe and secure,” Ms Elphicke said in a statement released by the Labour Party moments before Prime Minsiter’s Questions.
“Lives are being lost in the English Channel while small boat arrivals are once again at record levels. It’s clear they have failed to keep our borders secure and cannot be trusted.”
Ms Elphicke was elected in 2019 after taking on the seat previously represented by her ex-husband Charlie, who stood down after being charged with three counts of sexual assault.
He was jailed for two years in 2020 and Ms Elphicke later spoke out in support of his appeal saying that although he had "behaved badly" she believed the sentence was "excessive".
Ms Elphicke has also faced criticism for suggesting footballer Marcus Rashford should have spent more time "perfecting his game" rather than "playing politics" after he missed a penalty in the Euro 2020 final.
The England footballer had waged a high-profile campaign over the provision of free school meals during the pandemic.
Ms Elphicke crossed the floor and joined Labour MPs behind Sir Keir Starmer at Prime Minister’s Questions on Wednesday.
It is understood she will step down at the next election.
Sir Keir 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?".
Ms Elphicke said: “Britain needs a Government that will build a future of hope, optimism, opportunity and fairness.
“A Britain everyone can be part of, that will make the most of the opportunities that lie ahead. That’s why it’s time for change. Time for a Labour Government led by Keir Starmer. The general election cannot come soon enough.”
Her defection follows former minister and Conservative MP Dan Poulter announcing he was joining Labour last month.
The MP for Central Suffolk and North Ipswich said he could no longer look his NHS colleagues and patients in the eye while representing the Conservatives.
Thursday’s high profile defection follows bruising local elections for the Tory party last week.
Almost 500 Conservative councillors lost their seats last week, while Labour won almost 200 seats.