At a snap press conference in London, the members of Parliament stood up one by one to explain why they have resigned in protest at Jeremy Corbyn’s leadership of the Labour Party. They will now sit in a new “Independent Group” and are aiming to become a new force in U.K. political debate.

The split has been rumored for months, but with less than six weeks until the U.K. is due to leave the European Union, Corbyn’s failure to take a decisive stand against Theresa May’s Brexit policy proved to be the “tipping point” for many in the group.

Chuka Umunna, Labour’s former chief business spokesman, said the mainstream political parties cannot be the answer and urged other politicians with doubts to join the new grouping. There has been speculation that some Conservatives will also split away from May’s party.

“Politics is broken, it doesn’t have to be this way, let’s change it,” Umunna told reporters at the press conference on Monday morning. “The established parties are simply not up the challenge. They can’t be the change because they have become the problem.”

Corbyn was ready for the announcement when it came. “I am disappointed that these MPs have felt unable to continue to work together for the Labour policies that inspired millions at the last election and saw us increase our vote by the largest share since 1945,” the Labour leader said in a statement.

He accused the Tories of “bungling Brexit” and insisted he had set out “a unifying and credible” alternative plan. “Now more than ever is the time to bring people together to build a better future for us all,” he said. DM