Speculation is rife in Westminster that a rerun election could be called as early as July if the result bears out polls suggesting no party will have enough MPs to form a majority government or a viable coalition.
This could make 2015 the first year with two elections since 1974, when Labour prime minister Harold Wilson called a second poll after eight months, successfully transforming his minority administration into a government with a slender overall majority of three.
Mr Clarke, who was a Tory whip in the run-up to the first 1974 election, warned that a second poll before the end of this year would be unlikely to give any party an outright majority.
“You can get out of a hung parliament by having a second election but, not surprisingly, the public tends to return a parliament which looks rather like the first one,” the former chancellor said
“You won’t necessarily find that if you hold it within a few months you will get a different result from the first one, so people need to make their mind up this time.”
Mr Clarke said a minority Labour administration relying on SNP votes to get its agenda through would be “ordeal by torture” for Ed Miliband. He said the 2015 election should have been a “walkover” for Tories, fuelled by economic recovery in the same fashion as Margaret Thatcher’s landslide in 1987.
“We have an economy that is doing well, has a long way to go, and we took over a catastrophe for which the Labour Party are still blamed by many people,” Mr Clarke said.
“Now it’s the cynicism and detachment of the population, the fashionable hostility to the political class and the somewhat larger number of people who are refusing to vote at all which is stopping that happening.”