Nick Clegg railed against Conservative backbenchers this morning, in a speech which saw him demand that David Cameron stop buckling to their demands and "get back to governing".
The explosive attack comes after several weeks of Conservative infighting over Europe and gay marriage, as the threat from Ukip on the Tories' right flank drags the party further away from the centre.
"Conservatives need to decide for themselves how they play their cards but if you constantly go on about the stuff Ukip wants to talk about don't be surprised if you help Ukip,"
Clegg told a gathering of journalists at a Whitehall press conference.
In a series of outbursts, the deputy prime minister attacked Tory backbench behaviour as "game playing", "navel-gazing", and "shrill".
And in a clear message to Cameron, he added: "Leadership is about sticking to your guns."
The deputy prime minister's press conference came as Cameron issued a radio interview in which he desperately tried to move on from the parliamentary manoeuvres over gay marriage and Europe which dominated the last few weeks in parliament.
"If you're an ordinary person, going about your daily business, what would you have seen if you tuned into Westminster over the last few weeks?" Clegg said.
"Westminster consumed by game-playing over Europe and gay marriage - MPs disappearing into a parliamentary rabbit warren, obsessing over this new tactic or that new trick: paving legislation, enabling referendums, wrecking amendments.
"Anyone watching would be forgiven for asking: what are these politicians doing?"
The comments reflect the growing irritation on Liberal Democrat benches at the Tory party's obsession over Europe and gay marriage.
"Of course Europe and gay marriage are important. But Britain is facing the most profound economic challenge in living memory," Clegg said.
"We cannot allow parliament to be clogged up by these matters simply because they cause the biggest political punch ups."
The speech also saw the Lib Dem leader assure voters that he can keep the coalition on the centre ground, despite the increasingly vociferous demands from a more Conservative agenda from Tory backbenchers.
"If you stand in the centre ground, rest assured: so long as I am deputy prime minister this coalition will not walk away from you," Clegg said.
The deputy prime minister also insisted the coalition will last up until the general election campaign, in a comment which dashed widespread expectations that the two parties would disentangle themselves six months or so before election day.
"I am absolutely committed to this coalition lasting until 2015 – as is the prime minister," he said in a speech in central London this morning.
"I know some commentators think it would be clever to duck out six months early. But that doesn't make any sense.
"The idea that the Liberal Democrats could suddenly win back those people who have never liked us going into government with the Conservatives is nonsense - as if we could pull the wool over people's eyes, using an early exit to somehow erase the previous four and a half years."
Asked if his party's support for next month's spending review meant the Lib Dems would be matching Tory tax and spend plans past 2015, Clegg answered: "No, of course not. Absolutely not."