Anna Soubry, Sarah Wollaston, and Heidi Allen will now sit alongside the eight former Labour politicians who quit their party to form the new “Independent Group” in Parliament earlier this week.

The three resignations are major political blow to the prime minister, reducing her already slim ruling majority and threatening to erode party discipline in the run-up to a series of crucial parliamentary votes on her Brexit plan.

May is due to head to Brussels later on Wednesday as she scrambles to get fresh concessions from the European Union in order to put a reformed divorce deal to a vote in the House of Commons as soon as next week.

It’s unclear how the new Independent Group of MPs will conduct themselves, and whether, for example, they will all vote the same way on key policies such as Brexit. The ex-Tories had already been voting against May’s divorce strategy.

Some of the group’s members want to become a new center-ground political movement to rival the mainstream Tory and Labour parties. There were signals, however, that the three Tories may not formally join the new grouping as full members.

‘Final Straw’

What is clear is that May’s approach to Brexit drove the Tory trio to give up the party she leads, and there’s speculation that others could follow.

“The final straw for us has been this Government’s disastrous handling of Brexit,” Soubry, Wollaston and Allen wrote wrote in a joint letter to May. “Following the EU referendum of 2016, no genuine effort was made to build a cross party, let alone a national consensus to deliver Brexit.”

They criticized May for trying to placate hardline Brexit-backers in her party, and abandoning the interests of the 48 percent of voters who backed staying in the EU in the referendum.

How a new political movement could change course of Brexit

“The country deserves better,” the three newly independent MPs said. “We believe there is a failure of politics in general, not just in the Conservative Party but in both main parties as they move to the fringes, leaving millions of people with no representation. Our politics needs urgent and radical reform and we are determined to play our part.”

The defections don’t immediately increase the chances of a general election. A national vote at this stage would probably be bad for these MPs, who don’t have a party, a leader or a policy platform. If anything, the effect of the creation of the Independent Group will be to reduce the number of MPs who would back a No Confidence motion against the government, because of the reduction of Labour numbers. DM