A letter is being circulated among Labour MPs this afternoon calling for a secret ballot on Gordon Brown's leadership.
According to one MP who would like Brown to leave office, the letter is being co-ordinated by a number of rebels, including the former cabinet ministers Charles Clarke, Patricia Hewitt and Geoff Hoon.
However, there are questions being asked as to whether any move can be made against Brown today, in the midst of heavy snowfall, as much of the UK has ground to a halt.
"It may not be possible because of the snow," one MP said. "But the idea is that, at the very least, it forces Brown to give a commitment that if he stays on to fight the election, he will not serve more than one year."
Brown scored an early hit against David Cameron at PMQs today when he mocked the Tories' new slogan, "Year for change", saying, in reference to Cameron caving in to the Tory right/ConservativeHome brigade on tax breaks for married couples: "He changed his policy in the morning, he changed his policy in the afternoon and he changed his policy in the evening." Cameron carped about and mocked the Budget deficit, but Brown rallied MPs. "Their policies are a change: a change back to the 1980s."
Cameron had a reasonable joke about saying "I love you, darling" and meaning it (unlike with Brown and the Chancellor) but -- uncharacteristically -- Brown hit back with a spontaneous joke of his own, about the married couple's tax allowance issue: "He can't even say I do or I don't!"
This may be the wrong day to move against Brown.
UPDATE: Hewitt and Hoon are set to issue a statement calling for Brown to step down.
UPDATE: Extracts from the Hewitt-Hoon statement:
* "Many colleagues have expressed their frustration at the way in which this question is affecting our political performance. We have therefore come to the conclusion that the only way to resolve this issue would be to allow every member to express their view in a secret ballot."
* "There is a risk otherwise that the persistent background briefing and grumbling could continue up to and possibly through the election campaign, affecting our ability to concentrate all of our energies on getting our real message across. In what will inevitably be a difficult and demanding election campaign, we must have a determined and united parliamentary party."
* "It is our job to lead the fight against our political opponents. We can only do that if we resolve these distractions. We hope that you will support this proposal."