Ahead of tonight’s first Republican primary debate, the Quinnipiac Poll out this morning has bad news for Rudy Giuliani (and Mitt Romney), good news for Fred Thompson, and mixed news for John McCain.

To the Ludicrously Early Poll Mobile, Robin! …

Quinnipiac polled 1,166 American voters between April 25 and May 1.

Compared to Quinnipiac’s last national poll in February, Mr. Giuliani fell to 27% from 40% — a huge tumble. Mr. Romney barely budged, going to 8% from 7%. Mr. McCain also barely budged, going to 19% from 18%. And Mr. Thompson burst onto the scene, coming in at 14%, having not been included in the last poll (and, as usual, stealing third place from Mr. Romney, despite not having lifted a finger).

So, the bad news for Mr. Giuliani is obvious: a big tumble, and the appearance that it has been caused almost entirely by Mr. Thompson stealing a big chunk of his support out from under him. The bad news for Mr. Romney is equally obvious: that he’s being overshadowed by a guy who’s not even in the race. As for the good news for Mr. Thompson: He’s doing great for a guy not doing anything.

What’s less obvious is why this is mixed news for Mr. McCain. Given that his support in this poll has hardly budged since February — when he’s just gotten finished with a major “re-launch” of his campaign — one might be tempted to call it unadulterated bad news. Sure, his main rival, Mr. Giuliani, has taken a hit, but he also now has to contend with Mr. Thompson nipping at his heels.

But, a little deeper down in the numbers, there are some positive signs for Mr. McCain. Specifically, look at Question 2 on this most recent Q-Poll. Mr. Giuliani has beaten the rest of the field among white Evangelicals in just about any poll I’ve ever seen. But when Quinnipiac breaks down this most recent poll and looks at white Evangelicals, Mr. McCain comes out on top with 21%. Mr. Giuliani is tied with Mr. Thompson at 17%.

Now, Quinnipiac doesn’t seem to have the same breakdown available for its February poll, so no direct comparison is possible. However, we can look at the two candidates’ approval ratings among white Evangelicals between February and May.

While Mr. McCain’s favorable-unfavorable ratings have deteriorated slightly with the public at large, he’s gained among white Evangelicals while Mr. Giuliani has seen an erosion. In February, Mr. McCain’s fav-unfav with white Evangelicals was 53%-24%; now, it’s 58%-15%. Among the same group, Mr. Giuliani went from 62%-16% in February to 57%-19% today.

These aren’t huge jumps on either side. But they are evidence that Mr. Giuliani’s liberal social views are catching up with him, while Mr. McCain is having some success reminding social conservatives that, though he’s had some spats with the religious right, his views aren’t that far out of the Republican mainstream.

All in all, a good week so far for Mr. McCain in the polls.