David Cameron bears ultimate responsibility for the Conservatives' defeat on boundary changes earlier this week, Peter Bone said today.
The rebellious backbench Tory MP stepped up his calls for the immediate breakup of the coalition after Liberal Democrat ministers voted with Labour against boundary changes earlier this week.
Interviewed for politics.co.uk's weekly podcast, the Wellingborough MP said the Lib Dems were "two-faced" - but suggested they would have backed down had the prime minister called their bluff.
"It was the prime minister's decision to allow the Liberal Democrats to do it, because he is responsible for the ministerial code," Bone explained.
"If he'd not given derogation, they would have had to have been out of government. While the prime minister said he was very angry about what had happened, actually if you look at it it's his responsibility and his decision to let that happen."
Earlier this month Cameron and Nick Clegg signed a specially drawn up memorandum giving up the Cabinet convention of collective responsibility, witnessed and minuted by the Cabinet secretary Sir Jeremy Heywood, for the boundary changes issue.
The move was avoidable, Bone claimed, because he believes Lib Dem ministers would not have been prepared to walk out of the government over the clash.
"There are some people who think the prime minister could have said, 'look Clegg - if you're going to do this you're out on your ear mate', and called his bluff," he said.
"Nobody believes the Liberal Democrats want to give up their red boxes and nice salaries and being very important people.
"They have no principles, as we know, because they've changed their mind on the in-out referendum, on tuition fees. If we'd made the threat... I don't think they'd have voted in the way they did. I think possibly the prime minister, in trying to carry on with the coalition at all costs, made a mistake."
Bone believes a switch to a minority government, with the Liberal Democrats back in opposition, is in the "national interest".
But his view was rejected by another Tory malcontent, Eleanor Laing, who said it would have been "too risky" for the prime minister to have called Clegg's bluff.
"At the moment what the country needs is stability, and much as I detest being in coalition with the Liberal Democrats I put my country first, above my own political feelings," she told politics.co.uk.
"Those of us who don't like being in coalition with the Liberal Democrats will just have to put up with it for the sake of the stability of the country."