Roundup: Search starts for new PM as Labour's Corbyn refuses more calls to quit

The first name was put forward at Westminster Wednesday in the search to find a new Conservative prime minister. Work and Pensions Secretary Stephen Crabb announced his candidacy for the keys to 10 Downing Street.

But across the floor of the House of Commons, the main opposition Labour benches remained in turmoil after leader Jeremy Corbyn clung onto his job, refusing more calls by senior party members to stand down.

Ed Miliband, who Corbyn replaced last fall as leader, was one of the latest to urge his successor to step down. Miliband described Corbyn's position as untenable.

Labour veteran Harriet Harman, who became acting Labour leader after Miliband quit also made a plea to Corbyn to go.

And in the first Prime Minister's Question time since Britons voted to leave the EU last Thursday, Prime Minister David Cameron also joined in the chorus of calls to Corbyn.

Cameron told Corbyn to resign as Labour leader, claiming it is not in the national interest for him to continue.

Cameron criticised Corbyn's efforts during the EU referendum, finally shouting to him across the floor of the house: "For heaven's sake man, go."

One of the likely challengers to Corbyn's leadership, former deputy leader Tom Watson announced late Wednesday that he will not mount a challenge.

Watson quit Corbyn's shadow cabinet along with virtually every other front bench Labour politicians in a determined demonstration of the opposition to Corbyn remaining in the top job.

Watson has been trying to persuade his former boss to go, insisting that the impasse was placing the Labour Party in peril.

Even a vote of no confidence by three quarters of Labour MPs was not enough to budge Corbyn, who stormed into the job last fall with massive grassroots support from Labour members across the country.

Corbyn has announced that if he is challenged he will stand again for the job, knowing that last year he garnered almost 250,000 votes, compared to the 80,000 his nearest rival, MP Andy Burnham, received.

Anti-Corbyn MPs insist that much the leader's support has diminished, mainly because many of his young supporters were supporters of Britain remaining in Europe. But Corbyn has responded by refusing to "betray" party members who backed him by resigning.

Watson's decision means that only one other senior MP remains as a front runner, Angela Eagle, MP for Wallasey near Liverpool. She stood down from Corbyn's shadow cabinet along with the twin sister Maria Eagle who had also been a front bench shadow minister.

Meanwhile in the Conservative camp, the Work and Pensions Secretary Stephen Crabb became the first to announce he will be bidding to become leader of the party, effectively the prime minister if he is successful. He said he will seek the leadership, promising a "One Nation" Conservatism.

Former London Mayor Boris Johnson is said to have the support of 100 Conservative MPs, with Home Secretary Theresa May also expected to stand.

Conservative candidates have until 12 p.m. (noon) Thursday to put their names forward.

The Conservative leadership race was triggered by Cameron's decision to stand down after he failed to persuade Britons to vote for remaining in EU in the historical referendum. Endit