From the Des Moines Register:

Mitt Romney still leads in Iowa but Fred Thompson, a relative newcomer to the presidential race, has emerged as his nearest competitor in a new Des Moines Register poll of likely Republican caucus participants.

Mike Huckabee and Rudy Giuliani are in a close fight for third place in the Iowa Poll taken over three days last week.

Romney, who has campaigned more often in Iowa than his Republican rivals, is the presidential choice of 29 percent of those who say they definitely or probably will attend the leadoff caucuses.

OK so it’s still 29 to 18 in favor of Romney but Thompson is now beating out Rudy which is something new in Iowa.

The numbers:

These are likely caucus voters which is more important. Romney is still dominating quite strongly. I am guessing that Fred Thompson’s performance at the upcoming debate this Tuesday will help or hurt him strongly.

Support for former New York Mayor Rudy Giuliani and Arizona Sen. John McCain has eroded.

Giuliani, at 11 percent, is in a virtual tie with Huckabee for third place. But his level of support was 6 points higher in the Register’s last presidential poll in May. McCain and Giuliani ran neck-and-neck then as the nearest challengers to Romney. Thompson wasn’t included in the May poll because he hadn’t declared his candidacy.

If this poll is reasonably accurate, Giuliani has serious trouble in Iowa at this point. He leads nationally but these early caucus states count so much more. McCain is basically a non-contender at this point.

Following the MSNBC Republican debate on Tuesday, the Thompson/Romney numbers could tighten.