The Evolution of John McCain continued yesterday as the senator backed out of voting -- either yea or nay -- on the DREAM Act, which he had previously sponsored. He could have voted if he'd wanted to, of course; the New York Sun reports that he "rearranged his campaign schedule to return to Washington yesterday for a vote on a judicial nomination, but he did not stick around for a key vote just an hour later."

Why would a man who staked part of his presidential ambitions on defending a path to legal citizenship duck out of a fairly unobjectionable piece of that agenda? DREAM would allow illegal immigrants who came to America before they were 16 (i.e., with their parents) to apply for legal residency as long as they've lived here for five years and have been through two years of college.

The problem for Fred Thompson and the other immigration panderers in the Republican field is that people who'd benefit from the law are precisely those who don't fit the mold of the lazy Mexican who speaks no English and brings disease over the border.

It doesn't matter, though. McCain has proved, again, the limits of his principles in the face of competitive pressure.