The Prime Minister confirmed that both parties would whip their MPs and peers to support the legislation, paving the way for an embarrassing rebellion early on in the life of the Liberal-Conservative coalition.
“I believe the time has come to move to fixed-term parliaments. If you have a fixed-term parliament, you must have some sort of mechanism that ensures it lasts for a fixed-term,” Cameron said.
The 55 per cent threshold means that even if the Liberal Democrats walked away from the coalition and formed a pact with the Labour party, they would not have the number of votes needed to bring down the government and trigger an election.
But Cameron and deputy Prime Minister Nick Clegg are facing strong opposition from Labour, as well as growing disquiet on the Tory backbenches.
Charles Walker, the Conservative MP for Broxbourne, has hit out at the plans, saying they are being introduced as a “convenience” for the Lib-Con coalition government.