Alongside this morning's debate on whether to support "Osbornomics", the Lib Dem conference will vote later today on whether to back the reintroduction of the 50p tax rate. While the main motion favours maintaining the current 45p rate, an amendment argues that the party should support the 50p rate, subject to a review concluding that the measure would raise more than it costs. Since the 50p rate, contrary to what some claim, raised £1bn in its first year (and would have raised more had George Osborne allowed it to operate for longer), the case for a Yes vote is a strong one. It would enable the Lib Dems to reclaim ownership of a policy they proposed long before Labour (abandoning it under Ming Campbell's leadership in 2006) and provide a powerful dividing line with the Conservatives.

When I interviewed Tim Farron, the Lib Dem president, for the New Statesman last week, he told me: "My view is that we should have that [the 50p rate] in our manifesto and while it raises an amount of money, it’s also a really important statement that we are all in it together." Polling by Liberal Democrat Voice has shown that 90% of party members support the principle of a 50p rate.

But asked on the Today programme this morning whether he favoured the move, Clegg said: "To drive home the message of tax reform I think changing one very specific symbolic tax rate is not really the key part of the matter." He suggested, however, that he was relaxed about the prospect of defeat: "Of course if the party votes to take a decision, that’s one of the joys of the Liberal Democrats...we still retain this thing called democracy and I’m very proud of the fact that I’m, in a sense, just one voice among many and that this is decided democratically."

In arguing for the retention of the 45p rate, Clegg will be aided by Vince Cable, who is due to speak in the debate, which begins at 3:30pm. With the party's pre-eminent economic voice publicly supporting the motion, many will be less inclined to vote for the 50p rate. But the weight of opinion in favour of it means that this could still be the moment that the grassroots choose to deliver a bloody nose to the leadership.