The Latest on British political developments (all times local):

9:15 a.m.

The competition for the Labour Party leadership has become more intense with the emergence of a third candidate.

Former shadow minister Owen Smith said Wednesday he will challenge embattled party leader Jeremy Corbyn and former Labour business spokeswoman Angela Eagle in the contest.

He says he would be a "radical and credible" leader.

Corbyn is fighting to retain his position after a dramatic loss of support among his party's members of Parliament.

The Labour Party executive committee has ruled that his name must be on the ballot despite his lack of backing among legislators. Corbyn is banking on support from rank-and-file members.

The winner will be announced in late September.

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9 a.m.

David Cameron will be appearing before Parliament as prime minister for the last time before handing over to successor Theresa May.

Cameron will step aside on Wednesday after losing the campaign to keep Britain in the European Union. He will take on his final session of prime minister's questions before traveling to Buckingham Palace to formally tender his resignation to Queen Elizabeth II.

Cameron told The Daily Telegraph it had been "a privilege to serve the country I love."

May will seek to calm the country, and the financial markets, after upheaval following the unexpected result in the June 23 referendum.

She will reportedly give priority to appointing a Cabinet minister in charge of implementing Brexit, the decision to leave the EU.