Newsnight's Political editor Michael Crick reports on a dramatic day in Westminster which saw Prime Minister Gordon Brown announcing he would step down as Labour leader - a move which appeared to be a last ditch attempt to wrestle the support of the Liberal Democrats from Conservative hands.

Mr Brown also announced that his party would begin formal coalition negotiations with the Liberal Democrats, forcing the Conservatives to up the ante, promising a referendum on a change in the electoral system.

Read Michael Crick's blog

Broadcast on Monday 10 May 2010.