Larry Kudlow

While Hillary Clinton is slipping in the polls, Rudy Giuliani is on a roll. This is a big swing of momentum. Even the latest Wall Street Journal/NBC poll puts the two frontrunners in a dead heat.

Sen. Clinton was hurt badly by her flip-flopping performance in last month's Democratic debate. America's mayor, on the other hand, just got a hugely important endorsement from the Rev. Pat Robertson. The message to social conservatives is clear: It's now OK to vote for Rudy.

Why Rudy? Robertson named out-of-control federal spending, appointing conservative judges, reducing crime and, perhaps most importantly, "the overriding issue (of) defending against (the) bloodlust of Islamic terrorists," as issues that strongly favor Giuliani. On the other hand, he called abortion -- something of a sticky subject for Giuliani -- "only one issue" of importance.

The endorsement also suggests that evangelicals are divided on 2008. Indeed, there's no monolithic movement in favor of any major candidate. This is critical. It means no third-party candidacy from the Christian right.

Recall that Bill and Hillary Clinton benefited enormously in 1992 when Ross Perot swiped 19 percent of the vote (most of those Republican) in the race against Papa Bush. And when Perot ran again in '96, he undoubtedly drained votes from Sen. Bob Dole. (I note that Bill Clinton didn't garner 50 percent of the vote in either of these elections.) But Robertson has very likely removed this dynamic. No third-party gifts for Hillary in 2008.

Robertson is a big score for Giuliani, right when he's gaining ground on Mitt Romney in New Hampshire. That said, Romney is still up 15 points in New Hampshire, according to Scott Rasmussen's poll, and 9.5 points, as per the RealClearPolitics average. So you know what? Good for Romney.

To be very clear, I am not picking sides here. I do think Romney is running a strong campaign. And he's gaining strength as a candidate. I also think John McCain is finding his sea legs on the campaign trail. Romney, McCain and Giuliani are all strengthening what they say and how they say it. But at this writing, Giuliani appears to be at the top of his game.

When I interviewed him last week on CNBC, it marked the fourth time we had sat down together this year. But something was different. Giuliani was more in command of a wide breadth of issues, while there was a lot less talk about his considerable accomplishments as mayor of New York City.

Larry Kudlow

Lawrence Kudlow is host of CNBC’s “The Kudlow Report,” which airs nightly from 7 p.m. to 8 p.m.