FIVE THIRTY EIGHT: Senate Update: Clinton Is Surging, But Down-Ballot Democrats Are Losing Ground.

In recent elections, more and more voters have been choosing candidates from the same party for president and Senate. That trend appeared to be holding true this year too, even with Donald Trump, unusual as he is, on the ballot. So as Hillary Clinton jumped out to a bigger lead in the polls starting after the first presidential debate in late September, we might have expected Democratic Senate candidates to poll better as well. That hasn’t happened — the chance of Democrats controlling the Senate is only 54 percent in our polls-only model and 56 percent in our polls-plus model.

Indeed, the races for Senate control and the White House have split.

Ann Althouse comments: “It makes perfect sense to me. The more clear it seems that Clinton will win, the more important it becomes to those who worry about her that she should be offset and balanced by a Republican-led Congress. It seems really risky to empower a President Trump with a same-party Congress, but once he’s not a threat, the risk-averse among us should gravitate toward a Republican Congress to put a brake on President Clinton.”

True, though honestly a GOP Congress isn’t really “same party” regarding Trump the way a Democratic Congress would be for Hillary. Too many anti-Trump types among mainstream Republicans.