Vince Cable effectively delivered an open invitation to Labour as he told Liberal Democrat activists to prepare for a decade in power.
The Business Secretary predicted another hung parliament after 2015 - and said the party should remain in government whoever topped the polls.
The comments came in a bullish keynote speech to the Lib Dem conference in Brighton.
As ministers continued to stress their achievements during two years of power-sharing, Mr Cable delighted the rank-and-file with a series of stinging attacks on his Tory colleagues.
He claimed to have seen off "headbangers" who wanted to relax laws on hiring and firing, saying sacking people was "an aphrodisiac" for right-wingers.
In one passage Mr Cable mocked the public school origins of the rivalry between David Cameron and London mayor Boris Johnson, and ridiculed chief whip Andrew Mitchell over his career-threatening spat with police.
"Most of our MPs will face Conservatives at the next general election," he said. "They face the enticing prospect of a Tory split. Now I don't know what Boris and Dave got up to in Eton - perhaps a pillow fight got out of control in the dormitories. I have been told, however, that jokes about social class are not good for the unity of the coalition. But as a mere pleb, I couldn't resist it."
He also ramped up demands for the Tories to agree to a "mansion tax", hinting that if the Lib Dems could not secure the policy in this parliament they would get it from Labour later. "I know it horrifies the Tory backwoodsmen but it is popular and right," he added.
The Cabinet minister played up to reports that he has been "flirting" with Labour leader Ed Miliband by text, pretending that a message had come through on his phone while he was on stage.
"I don't believe actually that the British people will want to entrust their future to any one party next time," he said. "And if Britain wants sustainable growth, competence with compassion, fairness with freedom and more equality not ever greater division, then that government must have Liberal Democrats at its heart."