As all the pundits have been pointing out, this year's Senate election contests favor the Republicans, who have spent heavily to improve their odds. Obama's declining popularity and ongoing economic sluggishness aren't helping the Democrats, though one can argue they're not that hurtful either.
One scenario had the Republican party continuing the infighting and self-destructive nomination of far-right candidates that hurt them so much the last two times around. This time, not so much. I think they've significantly upped their odds of taking control of the Senate. The odds of them losing the heavily gerrymandered House are minuscule. So we'll have two years of (even more) split government, with the Executive in Democratic control and the Legislative in Republican hands. Although I rarely agree with Republican plans and ideas, I'm not convinced this is an entirely bad scenario.
First of all, I think that split government will actually improve the chances of a Democratic presidential win next time. US voters are extremely reluctant (historically) to give one party all the power. Losing both houses of Congress tends to energize the other party's base, and the Democrats will need an energized base both in terms of voting and in trying to replicate the Obama campaigns' successes raising large amounts of money from many smaller donors. The current estimate of the cost of a presidential campaign is around a billion dollars, and the Democrats will have to work through primary campaigns as well. Given how wide open the Supreme Court has thrown the floodgates, I think that billion is a low estimate.
Second, and more interestingly, it puts the Republicans in a new position. Previously, they had to keep a fearful eye on their right flanks, which lowered their chances/desires to compromise with Democrats. I've been saying for years that the reduction of the Republican party to "The Party of No, Especially When It's Something That Scary Black Guy Likes" is bad for all of us.
Our government seems unable to break out of two-party centralized gridlock. People on the edges, from Libertarians to Greens, have new ideas that aren't getting aired in the legislative debate. Even Obama's signature legislation, the ACA, is a far weaker and more flawed bill than it could have been. The Democrats had to ram through the only possible bill they could get because the alternative was more endless stalemate. We can't even manage to fix some of the most obvious brokenness now because of the endless efforts to repeal it entirely.
I believe that once the establishment Republicans feel they can fend off right-wing loony challenges they'll be willing to return to a more nuanced and cooperative form of legislating. I might be dreaming, but history seems to show it's possible.
One wildcard in all of this are the Tea Party no-longer-freshmen. They also got through their primaries and most will return to the House and Senate in November. If they continue to play Loony Tunes they could be very destructive with a majority in both houses. Or they could decide that they were elected to govern, not destroy, and we might get some things done. About this I am less optimistic, but Boehnor has shown he's fed up with the crap, and Cruz's Senate colleagues have already been willing to vote against him when it's in their party's interest. So perhaps the adults in the party will continue to reign in the children.