Even as he continues to hold a convincing lead in the national race, Rudy Giuliani may be riding for a big fall in Iowa and the other early state primaries. Mitt Romney, despite his anemic national showing, could sweep Iowa, New Hampshire and Michigan, a trifecta that could give him such momentum as to sweep him to the nomination.

The numbers are scary for Giuliani (and since Mitt doesn’t have a prayer in hell of beating Hillary in a general election, scary for us all). While he holds a lead in the national polls (Giuliani 30, Thompson 17, McCain 15, Romney 12, Huckabee 9 — all data is from the average of the past five polls posted on www.realclearpolitics.com), he is trailing badly in all the early states.

In Iowa, the first caucus, it’s Romney 29, Huckabee 15, Giuliani 13, Thompson 12, McCain 8. And New Hampshire isn’t much better. There it’s Romney also in the lead with 32 percent, Rudy a distant second at 21 percent, McCain at 16 percent, Huckabee at 7 percent and Thompson at 5 percent. And Michigan, which might be just a few days after New Hampshire, shows Romney also in the lead at 25 percent with Rudy at 20 percent.

So what will happen to Giuliani if he loses Iowa, New Hampshire and Michigan? South Carolina, the most conservative state in the nation, won’t be a stopper for him (he currently is tied with Romney at 19 percent, with Thompson at 18 percent). If he loses the first three contests, he’ll get creamed there.

The question will then become: Can Florida hold for Rudy? Right now, he has a comfortable 33-16 lead over Romney, but how will his candidacy fare after four straight crushing defeats?

Rudy has brought this crisis on himself by foolishly running no television ads in any of the early primary or caucus states while Romney has advertised for six to eight months. In a classic hare-versus-tortoise scenario, Giuliani waited so long to show his colors on television that Romney may have built up an insurmountable lead in the interim.

Rudy could still bounce back in Iowa if he gets his act together there and at least make it close. More possible would be for Huckabee, who has been surging with no money, to close with Romney and win in Iowa. Mike’s consistent pro-life position contrasts sharply with Mitt’s flip-flop-flip on the issue and could propel Huckabee ahead of Romney, particularly in light of the former Arkansas governor’s announcement that he is going to spend $1 million on Iowa ads.

But if Romney wins in Iowa, he will certainly win in New Hampshire — where he already leads — and in Michigan, where his father was governor and he has been working hard. Coming into Florida with that kind of momentum will make it very hard for Giuliani to come back.

But not impossible. National front-runners like Rudy and Hillary can survive shocks along the road, recover their balance and go on to win. Bill Clinton lost New Hampshire in 1992 and George W. Bush lost it in 2000, but each ended up doing pretty well. A candidate who is back in the polls usually can be knocked out by an adverse result in an early caucus or primary. But a front-runner usually has to be defeated one state at a time in dozens of states to be upended.

Republicans might recover their senses in time and realize that with Hillary on the ballot for the Democrats (most likely) it is no time to experiment with America’s tolerance and see if a Mormon can be elected president. With only 36 percent of the nation’s voters saying one can prevail, it would be an uphill fight. Is this truly the year the GOP wants to be saddled with a latter-day version of Al Smith in 1928? More to the point, Hillary would eat alive and spit out Romney by attacking his total inexperience in foreign policy and his current pro-life position. She won’t even need the anti-Mormon bigots to beat him.

So Republicans might pause to reconsider what they are about to do before they hand Romney the nomination. But with the extremely short lead time between Iowa and the rest of the nation’s primaries, who knows if there is enough time to stem such momentum?

Morris, a former adviser to Sen. Trent Lott (R-Miss.) and President Bill Clinton, is the author of Outrage. To get all of Dick Morris’s and Eileen McGann’s columns for free by email, go to www.dickmorris.com.