A new estimate from Nate Silver gives Republicans a 60 percent chance of winning a Senate majority in November. That’s a bit higher than the Upshot model (53 percent), and somewhat lower than the fairly confident projection from the Washington Posts’s Election Lab (82 percent). The Post’s version relies mainly on fundamentals; the other two give more weight to current polling. On balance, it’s fair to say that Republicans are more likely to get to 51 seats than Democrats are to keep 50 or more seats, but neither result would be surprising.

Keep in mind, however, that every seat counts in the Senate, so a 51-49 Republican advantage is a very different situation than a 55-45 advantage (which is possible if everything breaks right for them). Similarly, a 50-50 Senate with Vice President Joe Biden breaking ties isn’t the same as he 53-47 advantage that strategists for the Democrats are still hoping for.

Some of this is obvious: Getting one defection from the other party to win a vote is a lot easier than getting three. We know there are many things that Ted Cruz and Tim Scott enthusiastically support that would draw a dissent from fellow Republican Susan Collins. And there are plenty of things that Joe Manchin won’t join on no matter how much his fellow Democrats Barbara Mikulski or Tammy Baldwin want them.

Of course, because it takes 60 votes to pass legislation in the Senate, and because the combination of a Republican House and a Democratic president severely narrow the possibilities of meaningful legislation being signed into law, one might argue that even large Senate majorities don’t matter much. That’s not quite true. The majority matters because it tends to control the floor, and therefore the Senate agenda — and the more one party can hold together a functioning solid majority, the more it can afford to shut out minority party amendments.

Beyond all that, however, is the importance that individual senators can have. The Senate isn’t the House, and any senator can have a serious substantive effect on what happens by forcing action on an issue, cutting a deal, or even changing the national discussion in some policy area. Even if that senator belongs to the minority party, or isn’t on the relevant committee.

So, yes, by all means pay attention to the fight for control of the Senate. But keep in mind that there’s a lot more to it.

[Cross-posted at Bloomberg View]

Jonathan Bernstein

Jonathan Bernstein is a political scientist who writes about American politics, especially the presidency, Congress, parties, and elections.