A lot of the midterm outlook simply comes down to exposure: which party has more of it, and in which chamber.

In the House, there are 111 (!!) competitive seats, according to the Classic version of our model – races where each party has at least a 5 percent chance of winning. Because the national climate favors Democrats and because Republicans control most of the seats in swing districts as a result of their strong performance in the 2014 and 2016 elections, the overwhelming majority of those are currently held by Republicans. Granted, some seats from among that list of 111 are fringy pickup opportunities for Democrats – but Republicans are playing a lot of defense in a lot of different types of districts.

Just the opposite is true in the Senate, where 26 of the 35 seats up for election this year are currently held by Democrats, including 10 Democratic incumbents running in states won by President Trump. With that kind of map, Democrats would have to catch almost every possible break to win the Senate, and that’s not usually how politics works.

In fact, Democrats’ odds continue to become longer in the Senate, with their chances down to about 1 in 6 in all three versions of our forecast. This is despite the fact that their position has become better in some individual races, as you can see in the chart below, which compares our current Senate forecast against the last time we did a version of this exercise two weeks ago.

Where Senate odds have changed Democratic chances of winning on Oct. 9 vs. Oct. 26 (as of 8 a.m.), according to the FiveThirtyEight 2018 Senate forecast Lite forecast (polls only) Classic forecast (polls+fundamentals) STATE 9-Oct 26-Oct CHANGE 9-Oct 26-Oct CHANGE Nevada 52% 38% -14 50% 40% -10 Tennessee 41 28 -13 29 24 -5 Mississippi special 23 17 -6 14 12 -2 Texas 23 18 -6 25 21 -4 North Dakota 14 9 -5 31 32 +1 Arizona 68 64 -4 65 62 -3 New Jersey 88 87 -1 92 90 -2 Indiana 68 69 +1 75 71 -4 West Virginia 88 89 +1 88 89 +1 Missouri 51 52 +1 57 58 +1 Minnesota special 85 87 +2 89 90 +1 Montana 79 83 +4 84 86 +2 Florida 57 75 +18 60 74 +14 Overall Senate 21 16 -5 21 17 -3 Races in which Democrats’ chances have consistently been greater than 95 percent or less than 5 percent in the Classic version of the forecast are not listed.

The Democratic outlook has brightened in Florida, for example, where incumbent Bill Nelson now has a lead in most polls and is roughly a 3-1 favorite to defeat Republican Gov. Rick Scott. It’s also gotten better in Montana, where nonpartisan polls have been relatively rare, but have continued to show Jon Tester ahead.

But other races look like bigger challenges for Democrats than before. In Nevada, Republican incumbent Dean Heller – the only GOP senator on the ballot in a state carried by Hillary Clinton — has pulled into a slight lead in the polls against Jacky Rosen. Although the polling has been mixed in Tennessee, most of it has gone against Democrat Phil Bredesen. A pickup in the Mississippi special election, always a bit of a long-shot for Democrats, now looks like more of a pipe-dream after recent polling there.





FiveThirtyEight Senate forecast update for Oct. 26, 2018

I realize that “some states are moving in one direction and some in the other direction” isn’t a great headline, but this nicely illustrates Democrats’ Whac-a-Mole problem in the Senate: Whenever they can start to feel a little better about their prospects in one state (Florida), another problem crops up (Nevada).

Nor is it really as though Democrats can curse their luck in the Senate. Sure, they’ve had a few bad breaks:

Scott entered the race and put up a vigorous challenge against Nelson, even if it now looks more likely than not to fall short.

Bob Menendez’s corruption trial has turned New Jersey into a semi-competitive race.

Al Franken’s retirement created an outside (and perhaps slightly overlooked) chance for Republicans to pick up a seat in Minnesota.

In North Dakota, Democratic incumbent Heidi Heitkamp has had a lot of self-inflicted wounds.

John McCain died after the deadline for a special election to be held this year in Arizona, which would have given Democrats a second opportunity to pick up a seat in that state.

But there have been roughly as many favorable or “lucky” developments for Democrats:

Bredesen and Beto O’Rourke have created legitimate opportunities for Democrats in Tennessee and Texas when those races didn’t necessarily look likely to be competitive at all.

Republicans nominated underwhelming candidates in several Midwestern states such as Pennsylvania, Ohio and Wisconsin.

The only Democratic retirement was Franken.

Republican Thad Cochran’s retirement created a special election and an outside pickup opportunity for Democrats in Mississippi.

And let’s not forget: the Democrats somehow won a Senate race in Alabama last year, thanks to a good candidate in Doug Jones and Republicans nominating Roy Moore.

It’s too soon to say the Senate is a lost cause for Democrats. A 1-in-6 chance isn’t good, but it isn’t zero, either. The scenario for a Democratic victory, however, probably involves a systematic polling error in which all of the polls are off in the same direction rather than Democrats clawing their way to victory on a race-by-race basis. The map was tough enough for Democrats that almost everything possible was going to have to go right for them to win the Senate, and it hasn’t.