As I've said all along, when it comes to health care the problem for marginal Democrats is that (1) they want the bill to pass, because they're better off if Obama is doing well (oh, and they may favor it on the substance, too); but, they don't want to be perceived as supporting a purely liberal bill -- and that, given the expected unanimous or near-unanimous opposition that results both from a ideologically well-sorted Congress and a rejectionist strategy by the Republicans, the natural cover of marginal Republican votes isn't going to be available.
That's the lens to see most of what's happened with health care -- the Gang of Six endless negotiations that served the purpose of showing Dems were serious about compromise, the fight over the public option once is became the symbol of the liberal approach, Obama's insistence on budget neutrality and the arbitrary spending target. It's all so that both Nelsons, Lincoln, Tester, and the rest of that group of fifteen or so Democratic Senators can go back home and say, "It wasn't a liberal bill" and have media and interest groups support them. That's why the recent announcements of support by various Republicans who don't have to worry about GOP primaries is more good news for Obama and reform supporters. As Benen says, it's about cover for Dems, not about lobbying current Republican Members of Congress.
The question I have is: why did they do it? I can think of a few possibilities. Financial: do any of them lobby or hope to lobby for groups (or firms) that want reform? Personal, negative: are any of these cases revenge on Republicans for old slights? Personal, positive: are friendships across the aisle facilitating some of this? Personal, substantive: it's possible, I suppose, that Frist or Dole or the Governator just have a patriotic desire to help the nation and believe this is the way to do it. Did the White House seek out these Republicans? Did the administration actively cut deals with them? Or did they just show up?
I've looked at some of the reported stories, and no one seems to tell us why it's happening. Hey, reporters! We want to know who deserves the credit (or blame) for this one!