Obama's illegal-alien initiative
Politically, I think it's much less risky than it appears. True, a hard line on illegal immigration is broadly popular (Arizona's tough 2010 law drew 51%-to-39% support nationwide), but those who feel so strongly about this as to actually vote against Obama over a move to stop deportations of people who came here as children and grew up here -- well, those voters were no doubt in the Republican camp already. This isn't going to cost us any votes we could otherwise have won. But it could boost Hispanic turn-out, which has historically been low, and thus help Democrats, especially in certain states critical to Obama's re-election.
Of more value, it will deepen splits among Republicans, by agitating and energizing the foaming-at-the-mouth far right just as Romney is trying to pivot to the center (and to make some appeal to Hispanics). Romney somewhat reassured the Morlocks during the primaries by talking tough on illegals, even managing to get to the right of Rick Perry on the issue during the debates. He's doubtless hoping the general electorate has forgotten this, but Obama has now reminded them. Romney's now making moderate noises, but it won't be enough to reassure the center, and the Republican rank-and-file will soon be back where we want them -- at each other's throats (sample comment thread here).
The right wing in this country is saddled with a large extremist fringe which is dogmatic, paranoid, ideologically purist, and further subdivided into several factions (teabaggers, Paultards, theocrats, etc.). This makes the right as a whole vulnerable to fragmentation and destructive infighting. We'd be wise to do everything we can to attack that weakness.