Mickey Kaus's post DREAM Act analysis, based partly on Roy Beck's take, which he calls a "cold-eyed and revealing post-game analysis" is that it was the Tea Party primary challenges that sent a message to Republican Senators:

"Going into the lame duck season, it looked as if the anti-DREAM forces might have their greatest success intimidating Democrats from reddish states who were up for reelection and wouldn't want to buck a rising anti-amnesty tide. But, in the event, that strategy mostly failed; only two of the 2012 Dems opposed DREAM. Nineteen other up-for-election Democrats held to the party line and supported it. Beck made up for that failure with a spectacular success among Republicans who had previously supported one form of amnesty or another and among Republicans who are up in 2012. Of the latter group, 7 out of 8 voted against DREAM, including at least three previous amnesty supporters. Why? Beck writes:

"I suspect one of the reason we did so much better with the smaller group of Republicans facing re-election was that they are more likely to believe that they might face Primary oppostion from within their own Party if they support amnesty."

Translation:The Tea Parties did it. Not only had they threatened establishment Republicans with primary opposition, but they had actually beaten one ... two ... three of them. Nothing like fresh heads on pikes to, er, reinforce a persuasive (to my mind) policy argument. Score one for losing Delaware Tea Partier Christine O'Donnell, who knocked off establishment pick Rep. Mike Castle (who voted for DREAM) in the GOP primary. Even score one for Alaskan Joe Miller. He probably alienated Republican Lisa Murkowski by beating her in the primary, and ultimately she won reelection anyway as a write-in. But that's just one lost Senate vote. By my count, Miller's primary coup may have helped gain around ten votes by terrifying GOP incumbents who might otherwise have been tempted by the prospect of a feel-good, bipartisan, MSM-approved pro-DREAM stand.

Democracy can be a wonderful thing ..."

It goes back to what I keeps saying about politicians who haven't seen the light, but have felt the heat—one of the Senators who voted against the DREAM act was John Sidney McCain. Of course, what Mickey Kaus is referring to as the Tea Party is what we think of as "the Republican party's white base," also known as regular Americans.[Tea Party Triumphs: The White Giant Is Stirring By Peter Brimelow, September 15, 2010]

And it's an important movement—Kaus points out that Dave Weigel was "wrong, hideously and revealingly and embarrassingly wrong, when he predicted Dems would not use the lame duck to try to jam through controversial legislation? "

But that's a minor point, suitable for Press Club gloating—I'd say that the DREAM act vote, along with the 2010 Republican victories, justifies applying the same expression ("hideously and revealingly and embarrassingly wrong") to David Frum's campaign to create a Republican Party that is safe for Arlen Specter.