Substantively, I'm pretty happy with the Elena Kagan nomination. Politically, though, I suspect the White House has made a mistake. The calculation seems to be that Kagan is their most confirmable pick. Why? Well, Senators like Orrin Hatch have said nice things about her in the past. Conservatives at Harvard like Charles Fried like her.
On the other hand, there are entry points to rile up the conservative base against her. There's Kagan's opposition to ROTC based on the military's discrimination against gays. She wrote a college paper that seemed vaguely sympathetic to historical socialism. Tea Party Nation has emailed its supporters calling her a "radical leftist."
Now, maybe these concerns will remain marginal in the face of a selection that enjoys the support of Republican elites. But the last 15 months have shown that, in the face of conservative outrage or organized Republican opposition, the support of a smattering of Republican elites tends to melt away very quickly. What Republicans are going to want to invite a Tea Party-backed primary challenge by voting to confirm Kagan? In the end, I think no more than a couple GOP Senators will be left standing. If the White House predicts a 70+ vote cakewalk, I suspect it's mistaken.