Fred Thompson, once hailed as a Republican saviour in the 2008 Presidential elections but more recently dismissed as a dud, last night survived his biggest challenge yet largely unscathed.

In a TV debate in Dearborn, Michigan, against rivals for the Republican nomination, he knew that every word would be scrutinised, having missed the five previous such forums because of his much delayed entrance into the race .

Some of his first answers betrayed signs of nerves and ring-rust. “We need to make sure we’re doing all we can to make sure we’re doing all we can,” he said in reply to a question about protecting the national security infrastructure. On other occasions he appeared curmudgeonly. “I don’t think anybody believes anything coming out of Washington any more,” he said about the economy, before adding: “It’s not all doom and gloom.”

The conservative columnist George Will has described Mr Thompson’s plunge into the contest last month as “more belly flop than swan dive”.

Others have suggested he is Bob Dole without the Viagra, a reference to the 1996 failed Republican nominee’s latest marketing venture, or compared his performance to that of Britney Spears at the MTV Awards when she appeared barely able to lip-synch her own song.

Mr Thompson has been criticised for a less than gruelling campaigning schedule, apparent ignorance of key issues including speaking of the “Soviet Union” as if it still exists — and a subdued speaking style which has seen him end one appearance in Iowa with the words: “can I have a round of applause?”

Dan Bartlett, who recently quit as a long-serving Whitehouse aide, suggested that Mr Thompson had become the biggest dud in the campaign so far, having given a “very incoherent and not very concise” explanation for why he is running for president.

But last night Mr Thompson, a former senator best known for playing world-weary figures of authority, such as District Attorney Arthur Branch in Law and Order, probably exceeded the admittedy very low expectations about his performance.

He was asked the type of question which has tripped up past presidential candidates: who is prime minister of Canada? “Harper,” replied Mr Thompson, after a momentary pause, “Prime Minister Harper.” For much of the debate Mr Thompson ended up on the side-lines watching his rivals clash bitterly over tax policy.

Rudy Giuliani said that he had cut taxes as Mayor of New York while Mitt Romney had raised them as Governor of Massachusetts. “The point is that you’ve got to control taxes. I did it, he didn’t,” said Mr Giuliani, “I led, he lagged.” Mr Romney flashed back angrily that his opponent was talking “baloney”. Mr Romney also had a well-prepared joke at Mr Thompson’s expense. Welcoming him to the debate, he said it was a lot like Law and Order with a huge cast, a series that goes on forever, and “Fred Thompson shows up at the end”.

Mr Thompson acknowledged the barb with a backhanded compliment of his own, saying: “And I thought I was going to be best actor on the stage.”

He has suggested that the Washington political establishment is holding him to a different standard than his opponents. He is currently second in national opinion polls for the Republican nomination with about 20 per cent support compared to 28 per cent for Mr Giuliani.

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