Who will win the Senate?

Every four years, politicians spur voters to the polls with invocations of "the most important election in our lifetime," or at least a generation. This year might actually live up to the hype.

There's the presidency, of course, with the added significance of a Supreme Court nominee whose name is all but on the ballot. But there's also the Senate. Republicans spent three election cycles chipping away at the Democratic majority, finally winning a 54-seat majority in the 2014 midterms.

Two years later, Democrats hope to reverse those losses in one sweeping election cycle.

Sen. Chuck Schumer, D-N.Y., the Democratic leader-in-waiting, has good reason for hope. Republicans are defending 24 seats this year, while only 10 Democratic senators are on the ballot. Eight of those Dems will cruise to reelection.

Of the Republicans, 12 are all but guaranteed to keep their jobs, and another six are likely. But there are another six seats in states swamped by the 2010 GOP wave, which are really Democractic territories that President Obama won in 2008 and 2012.