MP Antoinette Sandbach, who was expelled from the parliamentary Conservative party last month, has joined the Liberal Democrats.
The Remain-voting MP was among 21 rebels who lost the Tory whip after rebelling against Boris Johnson in a bid to prevent a no-deal Brexit.
She will stand as a Liberal Democrat candidate in her Eddisbury constituency in December’s general election.
The move makes her the eighth MP to have joined the party this year.
Announcing her decision, Ms Sandbach said: “People have a very clear choice, the Conservative party offers years of uncertainty whilst the Liberal Democrats will stop Brexit.
“I will stand on my strong local record, helping to secure local investment, fighting for fair funding for our schools and to secure additional funding in local health services.
“Our country deserves so much better than Boris Johnson and Jeremy Corbyn”.
Ms Sandbach was not among the 10 rebels readmitted to the party last month, shortly before the Commons backed the legislation to approve the 12 December election.
Earlier this month, she lost a confidence vote among her local party members.