Prime Minister Gordon Brown says he is to step down as leader of the Labour Party as the battle to form the UK's next government enters its critical phase.
Why has Brown made this announcement now?
His hand appears to have effectively been forced by Liberal Democrat leader Nick Clegg, who did not want to begin substantive talks about the formation of a possible coalition government with Labour while Mr Brown was its leader, fearing he would be seen as propping up an unpopular prime minister who has been rejected by the majority of voters in Thursday's general election.
What happened to the Lib Dem talks with the Conservatives?
The BBC understands there are are no plans at the moment for Tory negotiators to resume their talks with the Lib Dems. The Conservatives have offered the Lib Dems a referendum on scrapping Britain's first-past-the-post voting system, which has long been a Lib Dem demand and it is now up to Mr Clegg to make up his mind. The vote would be on a switch to the
Alternative Vote system
, not full proportional representation, but the same as that being offered by Labour - and further than many in the Tory party wanted to go.
Could Labour and the Lib Dems form a government?
They could not form a majority government on their own. To command a majority in the Commons, they would need a combined total of 326 MPs and they only have 315. However, as Sinn Fein are unlikely to take up their five seats, the notional majority required would fall to 323. The two parties could stitch together a "rainbow alliance" with the SDLP, Northern Irish Alliance, Green Party, Plaid Cymru and possibly also the Scottish National Party. But given the number of participants, and their competing priorities, this could be an unstable coalition, which could well end in another general election sooner rather than later. Senior Lib Dems made clear on Tuesday they did not back a "rainbow coalition". They say it would be a straight Labour/Lib Dem coalition which would rely on the nationalists not to vote with the Conservatives to vote them down.
When will Brown be replaced as Labour leader?
There will be a leadership contest - the first in the Labour Party since the one Tony Blair won in 1994. Mr Brown has said a new leader will be in place by the time of Labour's annual party conference in September. He has urged Labour MPs not to begin nominating candidates or campaigning just yet, but it will be down to individual MPs as to whether they abide by his request or not. David Miliband, one of the leading candidates, has said he will do so.
How are Labour leaders chosen?
Labour leaders are decided by an electoral college which is split three equal ways between Labour MPs, party members and members of affiliated trade unions, on a one member one vote basis. It is thought that Labour's ruling National Executive Committee will finalise the procedures and timetable for the leadership election later this month.
When will Brown actually step down as PM?
He could remain at Number 10 for some time. He said in his resignation statement that he wanted to remain until he has formed a government in coalition with the Liberal Democrats, which could take anything from a matter of hours to days or weeks, but he added: "I have no desire to stay in my position longer than is needed to ensure the path to economic growth is assured, and the process to political reform we have agreed moves forward quickly."
What happens now?
It is down to the Liberal Democrats to decide whether they want to strike a deal with the Conservatives or Labour. Conservative leader David Cameron has said it is "decision time" for the Lib Dems while a senior Lib Dem figure has said the next 24 hours will be "crunch time". If they agree to work with a Conservative government, Mr Brown would be expected to go and see the Queen and step down with immediate effect as prime minister. If they reject the Conservatives but strike an agreement with Labour, Mr Brown can continue as PM until his successor as Labour leader is chosen.
Can David Cameron not just go it alone in a minority government?
The Conservative leader may have many more MPs than any other party, and may have won 7% more votes than Labour in the election, but he cannot become PM as long as Mr Brown stays in Downing Street trying to agree a deal with the Lib Dems and other parties. Should the Lib Dems reject both Conservative and Labour offers, Mr Cameron would be likely to end up leading a minority Conservative government.
What other option is there?
If there is no agreement between the different parties, then there is always the option of a second election being held sooner rather than later, as happened in 1974.