Veteran Hollywood actor and ex-US Senator Fred Thompson has declared he is seeking the Republican nomination for the 2008 presidential election.
"I'm running for president of the United States," he announced in an appearance on a popular chat show.
He joins eight other Republican candidates, including frontrunners Rudy Giuliani and Mitt Romney.
The move came as the eight took part in a 90-minute televised debate in the key election state of New Hampshire.
Mr Thompson made the widely anticipated announcement during a taped appearance on the Tonight Show with Jay Leno.
The BBC's Justin Webb in Washington says the former senator from Tennessee is enormously popular on the right of the party where he is seen as a new Ronald Reagan.
He is known for his conservative views on issues like abortion and gun control.
But the 65-year-old is probably best known as an actor.
He has played the president on screen, and is currently the district attorney in the popular TV series Law and Order.
The candidates taking part in the New Hampshire debate welcomed Mr Thompson to the race - but some derided his late entry into the race.
"The only question I have for Senator Thompson is 'Why the hurry, why not take some more time off", Mr Romney said.
"Maybe even January, February might be a better time to make a final decision about getting into this race."
Another candidate, Mike Huckabee, a former Arkansas governor, said: "I was scheduled to be on Jay Leno tonight, but I gave up my spot to somebody else because I'd rather be here in New Hampshire."
The New Hampshire debate took place ahead of the release next week of a crucial report by the Bush administration on the Iraq war.
Most contenders defended President Bush's strategy of "surge" in Iraq and rejected calls for a quick withdrawal.
Rudy Giuliani (L) and Mitt Romney are among the frontrunners
Campaigning for the November 2008 election is expected to gather pace in the coming months.
The primary season, in which the parties in each state nominate their chosen candidate to run for president, will get under way in January.
Mr Romney, a former governor of Massachusetts, is likely to want to build on his win in the Iowa straw poll in August, an indicator of strength in a crucial primary state.
Mr Giuliani, a former New York mayor who like Senator John McCain chose not to take part in the straw poll, continues to lead national polls.
Mr McCain was an early frontrunner, but his campaign faltered over the summer after disappointing fundraising figures and a shake-up of his operation.