Republicans, devouring their own
First, 2014. The historical pattern is that a two-term President's party normally sees its share of House seats drop in the mid-term election of his second term. This has been the case with every second-term midterm election since the Civil War -- except one. The exception was 1998, under Clinton -- the most recent Democratic President before Obama, which makes it perhaps a relevant precedent. Admittedly, the Republicans at that time were in the midst of obsessively trying to blow up the Monica Lewinsky affair into a major scandal, an endeavor which exasperated the public and may have cost the Republicans some votes -- but the Republicans of today are, if anything, even more prone to clutch at such straws of ersatz scandal (see Benghazi).
They're also prone to damaging themselves in other ways, such as the recent defeat of gun background checks, which was yet another exercise in opposing anything Obama supports, as Senator Toomey recently admitted. Obstructionism for the sheer hell of it doesn't play well with voters, especially on a proposal which 91% of them supported. I don't know how much impact the background-check débâcle will have on an election which is still 18 months away, but the odds aren't bad that they'll pull one or more further such self-immolating stunts closer to voting time. Right now the polls actually favor us, which doesn't guarantee anything, but it does limit the Republicans' margin of error for recovering from blunders.
As for the Presidential election in 2016, most polls show Hillary Clinton utterly obliterating any Republican opponent, even being competitive in states like Texas and Georgia. I'm not so sure she'll run -- she'll be 69 on election day and, if victorious, would be 77 at the end of her second term. But people who would vote for one Democrat would likely at least consider another; and Obama, his legacy at stake, will be putting his not inconsiderable campaigning prowess and organization to work for the nominee. And there's another factor at work.
2012's Republican primary season resembled a cross between a clown show and a demolition derby, with a field of mostly colorful but un-serious characters being slowly winnowed down as the teabaggers and religious nuts tried and rejected one not-Romney after another. For 2016, right-wingers seem convinced they have a much stronger field, but there's a quite different dynamic at work; they've started the demolition derby long before the primary season gets here.
First, Chris Christie, one of the few major Republican figures with a demonstrated ability to appeal to large numbers of Democrats, was demonized for working with Obama in the wake of Hurricane Sandy, and recently again after once more praising the President. The consensus of the hard-right base is that Christie is finished as a Republican Presidential contender.
Next came the turn of Marco Rubio, who until a few weeks ago was being lionized as the party's great 2016 hope among those convinced that (a) the key to party revival is to do better with Hispanics and that (b) the way to achieve this is to nominate a Hispanic candidate. Now, though, Rubio is being demonized for his support for the current illegal-immigration reform plan. The vehemence of the histrionics I'm seeing across the wingnutosphere suggest that he, too, is now out of the running for 2016.
At this rate, before 2016 even arrives, every plausible Republican Presidential candidate will have been excommunicated and struck from the list of possibilities for one sin or another. What are they going to do then? Run Palin? Let's also not forget factors like the hysterics of the religious-nut element over the party's tentative efforts to move to the center on gay marriage, or how the attacks on Rubio are likely playing among those Hispanic voters the party needs to attract. As I've said before, if the Republican party were a centipede, it would still be running out of feet to shoot itself in.
We're not guaranteed to win 2014 and 2016. But they're ours to lose.
Update: Republicans' Hispanic outreach threatens to blow up in their faces.