Some people are arguing that now is the time for the opposition to table a no-confidence motion. The Leader of The Opposition has made it clear she will facilitate one if Labour MPs now want to get rid of the PM. The Opposition is of course free to do this but will only do so if it seems likely there are enough Labour MPs to make it a worthwhile thing to do. Often the Opposition tabling a motion simply unites the governing party to fight off the threat to the future of the government. This defers the infighting which the crisis has generated. MPs in a governing party are usually reluctant to vote to destabilise their own patronage machine or to hasten an election.
Of course if enough Labour MPs see a No Confidence motion as a means to rid themselves of an unpopular leader then the Opposition can help the rebels by tabling and voting for such a motion. When a party has such a large majority as Labour there is no chance of passing a No confidence vote without large numbers of Labour MPs voting for it. If that did happen the King would ask whoever emerges as the new Labour leader to form the next government. It would not bring on an early General Election.
The Labour Party at the moment is very divided with a large number of Labour MPs extremely unhappy about their leader and about the events surrounding Lord Mandelson. So far the rebels have not all agreed to get behind a single candidate as an alternative to the Prime Minister. Instead the leading contenders or their supporters are busy attacking the Prime Minister in their briefings and doubtless seeing how many other MPs would be willing to get behind a leadership bid by them. It takes 81 Labour MP s to all declare in public they want the same named replacement as Leader to trigger a contest.