The average American does not understand this basic fact about our government: it makes a huge difference which party has the majority in Congress, and when we vote for this or that candidate in Congress, we’re voting for a party to be in power, regardless of the personality or even the policy preferences of the individual on the ticket. (This, by the way, is why in so many presidential debates, even when things are “normal,” it’s so customary for candidates to say “I will” when they really mean “I will ask Congress to,” because they’re playing to people who just don’t get how lawmaking works, and think the president can be credited or blamed for everything that moves in Washington.)
For much of my lifetime, I was so used to the Democrats having the majority in the House of Representatives that I could scarcely imagine anything else being possible. The Republicans had the Senate for Ronald Reagan’s first six years, starting with the 1980 election and ending with the 1986 election, but the Democrats won the House in the 1954 election while the Republican Eisenhower was president, and the Republicans did not win it back until 1994. Then, the Democrats retook both chambers in the 2006 election. In 2008, of course, Obama won the presidency, and for the first year of his term the Democrats had not only a majority in both chambers but a 60-vote supermajority in the Senate. But in 2010 the Republicans retook the House, and in the most recent congressional election, 2014, the Republicans got a majority in the Senate.
Now, let’s consider this year’s election. There is no realistic chance that the Democrats will retake the majority in the House; the Republicans redrew the districts after the 2010 census to make that virtually impossible, and they may well have a secure majority in the House for many years to come. But the Senate could go either way. The probability keeps going back and forth. The Democrats have a slight advantage: essentially, in the 538 projections, the Democrats bounce back and forth between being modestly favored versus being essentially tied. And that figure does more jumping around from week to week than the presidential race.
When it comes to passing legislation, you can expect to see more gridlock if one party does not control the House, the Senate, and the White House, and it needs to be remembered on that score that no party actually controls the Senate without a 60-seat supermajority to shut down filibusters. But a simple majority in the Senate alone can make an enormous difference on one specific point: the confirming of federal judges nominated by the president. As we have seen federal judges, like it or not, are very much policy makers, and a huge chunk of national policy is in their hands, and at the moment there are numerous judicial seats going vacant–Scalia’s seat on the Supreme Court is just one of them–because the Republicans in the Senate won’t even hold hearings on President Obama’s nominees.
Therefore, as we watch this election, even though the lion’s share of the attention is on Clinton and Trump, we need to be paying close attention to the question of whether the Democrats can regain a majority of seats in the Senate.