Today should have been a good day for the Prime Minister. Labour had won the first round of election-year battling after David Cameron reversed his position on tax breaks for married couples. Having first said they could not be guaranteed because of the scale of the Budget deficit, he (characteristically) caved in to pressure from the Tory right, an army of ConservativeHome bloggers and the traditionalist former leader Iain Duncan Smith.

Yet, while a number of MPs claimed that Gordon Brown would now survive this crucial month -- the last chance for any internal coup -- the rumblings have continued. While Brown was on retreat at his constituency home in Fife, a series of calls and messages had been exchanged between ministers and backbenchers over the leadership.

Then a rumour emerged that another cabinet minister was set to resign over Brown's leadership. The subject of that rumour was the "Blairite" Olympics minister, Tessa Jowell, but Downing Street received an assurance on the phone by her that she was staying. "Tessa is in a good place with Gordon at the moment," said a well-placed source.

Nonetheless, Brown remains "paranoid" and "obsessed" about the prospects of a move against him, according to one ally.

He was visibly relieved by recent polls showing a Labour upturn in the polls, especially a pre-Christmas report in the Guardian under the headline "Labour back in the race". But Brown has also reacted angrily to specific polling showing that he himself is unpopular, a liability. And it was in defensive mode that he emerged into the limelight, appearing on Andrew Marr's BBC show with his hands clenched awkwardly to his knees.

"The only real issue about the leadership now lies in the bunker itself," one supportive party figure says. "The plotters can't get their act together, but the question is whether Gordon can."

Meanwhile, Downing Street insists this is simply "tearoom gossip". And while it is true that the rebels, led by Charles Clarke, know that this is their "last throw of the dice", it appears that Brown will remain Labour leader into the election.

The main problem no anti-Brown Labour figure has ever been able to resolve is how there could be a second "smooth transition" of the leadership, a question that becomes more acute every day in the run-up to the election this spring. Lord Falconer, no fool, maintains that a contest -- avoided in 2007 -- would be "healthy". But he is practically alone.

The reality is that Labour would implode into a full-scale leadership contest involving several or all of the following: David Miliband, Ed Balls, Harriet Harman, Jon Cruddas, Alan Johnson and maybe Ed Miliband. Brown would not be in a position of strength to ensure a successor of his choice. And Balls would not tolerate that transition to any figure other than himself.

Instead, the only prospect of Brown's removal -- which surely must, if it is going to happen, come within ten days from now -- is for him to step down voluntarily. Some say that this would take a private appeal from those unlikely allies, Peter Mandelson and Balls. One MP tonight wistfully floated the idea that Brown could "miraculously" be found a "saving the world" job such as head of the International Monetary Fund.

The plotters whinge that the Labour movement should not have to go down because of the ruthlessness and political vanity of one man.

But, as one MP said tonight, "they have no balls". This is not quite fair: David Miliband, for example, the most credible candidate to replace Brown before the election, has judged that the carnage that would ensue from his resignation as Foreign Secretary would not be in the interests of the party. The cliché that he is a "bottler" is not accurate. The situation -- like Miliband himself -- is more complicated than is assumed.

What is clear, however, is that there is nothing in the history or psychology of Gordon Brown indicating that he would have fought bitterly with Tony Blair for ten years, and endured such abuse as Prime Minister for two, only to give up the chance of fighting a general election he still genuinely believes he can win.

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