A new CNN poll out today has Rudy Giuliani at 25%, which is his lowest point all year. John McCain, meanwhile, remains in second place at 23%, with Fred Thompson (13%) and Mitt Romney (10%) filling out the top tier.

Before getting to Giuliani, we should first take into account how little movement has occurred among the rest of the field. McCain has been sitting at around the low-20s since March, similar to the way Romney's been stuck in the low teens. Thompson's 13% is mostly old news by now, and we're probably witnessing a support ceiling for the former senator until he announces (or at least makes it all but certain that he will announce). Romney's stagnation, nationally at least, must be upsetting to the campaign, which has been publicizing recent good news hoping to generate a bit of momentum (e.g., strong first-quarter fundraising numbers and a solid first debate performance). And I'm sure McCain's folks take their candidate's closing the distance with Giuliani as bitter sweet, since it's mostly due to Giuliani's decline rather than McCain's rise.

As for Giuliani, his shrinking lead is not necessarily a surprise, although the reasons for it might be starting to worry the campaign. Good cases can be made on both sides of whether Giuliani's social liberalism is/isn't well-known among Republican primary voters. For example, Giuliani rests his candidacy not only on his performance on 9/11, but also -- and in many ways more importantly -- his performance in revitalizing New York using conservative solutions (e.g., welfare reform and a crack down on crime). But if you make the case that his pre-9/11 years contributed to his early lead, wouldn't you also have to say that voters were just as aware of his social liberalism? In other words, if you knew, for instance, in 2000 that Giuliani reduced New York's welfare rolls by 600,000, wouldn't you also probably know that he supported public funding for abortions? Were this the case of course we would have to find another reason for Giuliani's return to earth.

But if that's not the case, then we have to consider if Rudy's appeal from January to now has been nothing more than the public's respect for his 9/11 performance and little else. Indeed, that performance might be enough to land him the nomination, but if that's what we're seeing the campaign should be worried. Because if all people know about you is what you did for a few (albeit historic) weeks in September/October 2001, it makes you extremely vulnerable. John Kerry, to pull one example, rested his presidential hopes on his Vietnam service the moment he appeared before the Democratic convention and uttered those ill-advised words, "Reporting for duty." I doubt Giuliani would be as foolish as to ever explicitly base his entire candidacy on 9/11 -- his references to it mainly fall on the need to stay on the offensive in the war on terror -- and we should note that criticisms of his performance have been out there for several years. The point is that if Giuliani's primary opponents see an opening to inform voters about his social liberalism, then they will at every possible moment.

We should also note that last month's CNN poll had Giuliani at 27% when most other polls had him still in the mid-30s. But we can't dismiss today's poll as an outlier entirely, if only because it follows a downward trend that puts the RCP Average for Giuliani at 29.2%, which means that Giuliani might have to start getting used to life in the sub-30s.