Conservative leader Michael Howard has called for Tony Blair to resign after MPs rejected the government's plan to detain terror suspects for 90 days.
Mr Howard told BBC Radio 5 Live the prime minister's authority had been "diminished" by the vote.
Lib Dem leader Charles Kennedy said Mr Blair had to learn to build cross-party consensus or he would increasingly look like a "lame duck" prime minister.
Mr Blair has said he will serve a full third term before stepping down.
Asked whether the prime minister should quit, Mr Howard said: "Yes - I think this has so diminished his authority.
"This was something which he went out on a limb on and, as a result, I say, overruled his home secretary.
"It's a very important issue. It's a very serious issue and what today has shown is that he no longer has the authority to carry his party on important issues of this kind."
Mr Kennedy said: "I hope very much he'll learn the lesson from this. If he doesn't then increasingly his premiership is becoming a John Major premiership, at the mercy of events, at the mercy of opposition, not just from other political parties but from within his own.
"And he'll be increasingly seen as a lame duck and lack conviction, credibility and the persuasion that a prime minister needs to take people with him."
Labour's Clare Short, who quit the Cabinet over the Iraq war, said Tony Blair only had himself to blame for the defeat and she hoped it would "speed up" his departure.
She told Sky News: "Tony Blair wanted to pose as the macho guy, being even more right wing than the Tories.
"He thought he would embarrass them and the House of Commons wasn't convinced and 49 Labour MPs voted for what they though was right despite the whips threatening them and twisting their arms. "It was a good day for the House of Commons."
But Labour MP Shahid Malik said: "It's not the government who has lost; it's the British people.
"The Tories and Lib Dems have got to examine their consciences on this issue. We have denied the police the resources they say they will need to keep the country safe."
Opposition parties and rebel Labour MPs opposed the 90-day plan. MPs voted instead to extend detention without charge for terror suspects to 28 days, an increase on the current 14 days.
Prime minister Tony Blair said the vote was a test of leadership for him and everyone in Parliament - but 49 Labour MPs voted against the government.
Liberal Democrat party president Simon Hughes said: "If you can't manage to get you own troops behind you when you have a majority of 66 in the House of Commons in the United Kingdom then there is something fundamentally wrong about his authority or his judgement about this case."
Labour MP Paul Flynn, who voted against the government, called the result a "renaissance" for parliamentary democracy.
He blamed the government's refusal to "compromise".
Lord McNally, the Lib Dems' leader in the Lords, said: "If the prime minister has been chastened tonight, it may be well for the health of parliament."
Scottish Nationalist Party leader Alex Salmond said: "The prime minister has just fallen off the high wire."
Labour's David Winnick, who proposed the 28 day motion, said it had been carried on merit alone.
He said Mr Blair had "full enthusiastic support" from the majority of Labour MPs and he advised any "clique" that might be plotting against the prime minister to "take a running jump".
"I totally reject that the carrying of my amendment, as far as I am concerned, is in any way aimed at the government or the authority of the prime minister," he said.