Say it ain’t so, Lisa, Part Two

Rich Lowry reports that a well-placed source in the Senate says Lisa Murkowski will run for the Senate as a write-in candidate. The announcement, according to Lowry’s report, will come tonight.
I like Murkowski, but I don’t welcome her candidacy or see why conservatives should support it. The Republican nominee, Joe Miller, is electable (with no Murkowski in the race, he cruises to victory) and solidly conservative. In addition, although I don’t know much about Miller, his credentials seem exemplary (West Point and Yale law grad, distinguished military career, and experience as a lawyer and judge). From a conservative perspective, then, there is no apparent justification for Murkowski’s candidacy even for those of us who like her.
Would Murkowski’s candidacy pave the way for the Democrat to sneak in? An Alaska source predicts that it wouldn’t, and that we’d see essentially a two-way race between Miller and Murkowski. But Democrats can win in Alaska, and have won at times in recent years even in the absence of a significant third candidate. A decision that opens up that possibility, however slightly, is an unfortunate decision.
Moreover, there’s a chance that, if Murkowski runs, the Republican leadership will take immediate punitive measures against her. If she then wins, it’s not clear to me that she will serve as a Republican.
What are Murkowski’s chances of prevailing? In an ordinary three-person race, I suspect they would be quite good. She nearly held off Miller in the Republican primary, and she is popular among independents. But Murkowski will be forced to run as a write-in candidate, and that, I imagine, will make it difficult for her to win. Let’s hope she re-thinks the matter before officially taking the plunge.
JOHN adds: Lowry’s source was right; Murkowski will try to hold on to her seat. This makes her, by my definition, a RINO–that is, a nominal Republican who puts ego over principle.