Former Conservative MP Antoinette Sandbach has joined the Liberal Democrats with just 42 days until the general election.
The Eddisbury MP is the fifth former Tory MP to join the Lib Dems in recent months, with three ex-Labour MPs having also joined the party in that time.
Ms Sandbach, a former criminal barrister, will contest her current seat as a Lib Dem candidate at the 12 December election.
She won the seat at the 2017 election as a Conservative candidate with a near-12,000 majority.
She said: “This general election will be the most important in my lifetime.
“People have a very clear choice, the Conservative Party offers years of uncertainty whilst the Liberal Democrats will stop Brexit.
“I’m so proud to stand alongside other Liberal Democrat candidates across the country to fight for a brighter future with Jo Swinson, our candidate to be prime minister.
“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.
“I can’t wait to get to work, win this election and then deliver for my constituents and our country.”
Lib Dem leader Ms Swinson, whose party now has 20 MPs, described Ms Sandbach as a “passionate campaigner” and a “fantastic candidate” at the general election.
“Her defection clearly shows that the Liberal Democrats are the strongest party of Remain and attracting support from right across the political spectrum,” she added.
“Antoinette is one of the millions of people who are tired of the two old parties, led by people who will take our country backwards, not forwards.
“It is only the Liberal Democrats that will stop Brexit and build the brighter future that our country deserves.”
Ms Sandbach voted to leave the EU three times under the terms of former prime minister Theresa May’s divorce deal.
She was effectively expelled from the Conservatives in September when she had the Tory whip withdrawn by Mrs May’s successor, Boris Johnson, for voting against his Brexit strategy.
The prime minister’s action came after Ms Sandbach joined 20 other Tory rebels in voting to block a no-deal Brexit, which he had claimed needed to be an option for the UK.
Ten of that group’s number had the Conservative whip restored this week, but Ms Sandbach was not among their number.
She voted in favour of Mr Johnson’s Brexit deal in principle a week ago, but then subsequently voted against the prime minister’s proposed timetable to pass the deal’s ratifying legislation.
This led the prime minister to “pause” the passage of his Brexit deal through parliament and renew his push for a general election, which will now come on 12 December.
Prior to joining the Lib Dems, Ms Sandbach had revealed her intent to stand at the election in her Eddisbury constituency as an independent candidate.
Earlier this month, she lost a vote of confidence among members of her local Conservative association.
Politics reporter @GregHeffer Former Conservative MP Antoinette Sandbach has joined the Liberal Democrats with just 42 days until the general election. The Eddisbury MP is the fifth former Tory MP to join the Lib Dems in recent months, with three ex-Labour MPs having also joined the party in that time.