Liberal Democrats could vote with Labour in favour of a mansion tax if Ed Miliband does not play "political games" with the issue, Vince Cable has suggested.
It was welcome that Mr Miliband had "seen sense" and adopted the long-held Lib Dem plan for a 1% levy on £2 million-plus homes, he said - calling it "a policy whose time has come".
But he said he suspected the Opposition would be unable to resist linking any Commons motion to its plans to revive the 10p income tax rate - scuppering any hope of a coalition-splitting vote.
Mr Cable also poured cold water on proposals being debated by his party to bring holiday home and buy-to-let landlords under the mansion tax or impose a wealth levy on possessions such as jewellery and paintings. A party panel had produced some "wacky" ideas for the 2015 general election manifesto but they were "most emphatically not party policy" and were almost certain to be rejected by activists, he said.
Mr Miliband said last week his party backed the mansion tax as a way to fund the reintroduction of the 10p rate, controversially scrapped by Gordon Brown. While not a pledge for the 2015 general election, it attempted to outflank both coalition parties, with Chancellor George Osborne under Tory pressure to reintroduce the 10p rate in his Budget in March.
Liberal Democrats - backed by the respected Institute For Fiscal Studies think-tank - argue that the Government's policy of reducing tax for low earners by raising the threshold at which income tax is paid is a more effective measure.
"I'm glad they've seen sense... it is an idea whose time has come. I think the Labour Party are probably playing political games but nevertheless it's welcome that they are endorsing it," Mr Cable told the Murnaghan programme on Sky News. Asked if the Lib Dems would accept Mr Miliband's vote challenge, he said: "It depends entirely how they phrase it. If it is purely a statement of support for the principle of a mansion tax I'm sure my colleagues would want to support it."
Conservative Party chairman Grant Shapps said raising thresholds was "the most efficient" way to ease the tax burden, and hinted the Tories would look at pushing it beyond the £10,000 target for this parliament.
Asked about the prospects of the Chancellor adopting the 10p rate, he told BBC Radio 5Live's Pienaar's Politics: "I'm not the Chancellor and I won't try and pre-empt him. But what I will say is I'm absolutely confident that we will reduce tax, not to 10% but to zero for even more people by the election, and it would be nice if we could get the Labour Party to actually vote for budgets which removed millions of people out of tax entirely.
"We have already said we would like to get it up to £10.000 and I don't think I would be revealing too much to say that our ambition might be to get it higher. Taking people out of tax entirely is the most efficient, best way to do this. I would love to do it."