As I sit down to make my final estimates about the 2018 midterm elections, I have no small sense of trepidation. The last time I attempted to forecast an election, I got it badly wrong. My failure to see what, in retrospect, I feel I should have seen coming in 2016 has made me consider whether my own partisan preferences and/or overconfidence in my own acumen blinded me to the fundamentals of that election.

I resolved after that election to go back to basics, to pay less attention to polls and to do what I have typically done best: to focus on the fundamentals and what I know about the socio-political makeup of each Congressional district and each state.

There are two key fundamentals I have been keeping in mind over the two years of the current cycle:

  1. Fundamentally, midterms are always a referendum on the president, and typically, when a president is hovering well under 50% approval ratings, his party loses badly.
  2. Special elections during a two-year cycle usually give a very solid indication how the next election will end up.

With that in mind, I think it is clear that Democrats will make major gains on Tuesday. I think it is extremely likely that they will win the U.S. House of Representatives, a large number of governorships currently held by Republicans, and a significant number of state legislative chambers. The U.S. Senate has always been an uphill climb for Democrats this cycle, simply because so many Democratic-held seats (26) and so few Republican-held seats (9) are on the ballot, providing minimal pickup opportunities for Democrats and putting Team Blue on defense all over the map.

So the easiest call of this cycle is that Republicans are likely to retain the U.S. Senate. I see Democratic pickups in Nevada and Arizona, and Republican pickups in North Dakota and Missouri. I will say that my confidence about Arizona and Missouri is slim: Arizona, fundamentally, is still a Republican state, and Missouri’s Democratic Senator, Claire McCaskill, has a history of surviving tough races. But I feel extremely confident about the outcomes in Nevada and North Dakota. I expect when the votes are in, the makeup of the Senate will remain 51 Republicans, 47 Democrats, and two independent Senators aligned with the Democrats.

This means that I expect several endangered Democratic Senators will hold on, including Joe Manchin (D-W.Va.); Jon Tester (D-Mont.); Bill Nelson (D-Fla.); Joe Donnelly (D-Ind.); and Bob Menendez (D-N.J.). It looks like Nelson and Donnelly have opened a slight edge at the end. Democrats are sending out alarms about the troubled Menendez, but it is difficult to see how he loses when Democrats are poised to pick up 3-4 of the five Republican House seats in New Jersey (more on that later). I expect Democratic voters in New Jersey to hold their nose and vote for Menendez, if for no other reason than the Garden State’s disdain for Donald Trump.

In governorships, I expect Democrats to have a big night. It is a slam-dunk that they will flip governorships in Illinois, Michigan and New Mexico. After that, it is a question of who has momentum and enthusiasm. All the signs out of the Midwest is that Democrats will do well there Tuesday, so I expect governorships in Iowa, Ohio and Wisconsin to flip from red to blue as well.

Andrew Gillum, despite recent revelations that are causing his camp heartburn, has the momentum in Florida, and I expect him to prevail to become the first Democratic governor of Florida since 1998.

I expect the governorships of Maine and Nevada to flip, with slightly higher confidence about Nevada.

Now, on to the heavier lifts for Democrats. Republicans in Kansas are sounding alarms about their governor’s race, but the last time they were in peril (four years ago) in the gubernatorial and Senate races, they pulled it out by larger margins than expected. Of course, this isn’t 2014, but the presence of a third-party candidate in the governor’s race leads me to believe that the GOP will narrowly hold on. I also expect that South Dakota is too Trumpy a state to elect a Democratic governor for the first time since 1974, and that Oklahoma is too Trumpy to anoint a Democrat as well.

I also expect that Alaska will flip from independent to Republican, narrowly. Despite independent governor Bill Walker’s decision to drop out in favor of the Democrat, former Senator Mark Begich, Walker will still inevitably win a small percentage of the vote, and that should probably be enough to prevent Begich from winning.

In all, it adds up to a net gain of nine governorships for the Democrats, and a net loss of eight governorships for the Republicans, leaving the states split at 25-25. But watch the following states: the aforementioned Alaska, Kansas, Oklahoma and South Dakota, as well as New Hampshire. And if you want a real long-shot sleeper, keep an eye on Idaho, where Democrat Paulette Jordan appears to be an excellent candidate, but in a state that is very deep Republican red.

State legislatures are not given much attention in the horse race coverage, but based on the current trends and historical performance, I expect the following nine legislative chambers to flip from Republican control to Democratic, narrowing the Republican advantage in legislative chambers controlled from 66-33 to 57-42.

  • Maine Senate
  • New Hampshire House
  • New Hampshire Senate
  • Connecticut Senate (from tied to Democratic)
  • New York Senate
  • Wisconsin Senate
  • Minnesota House
  • Iowa Senate
  • Colorado Senate

If these gubernatorial and legislative forecasts are correct, Democrats would go from full control of eight states to full control of 14 states; Republicans would go from full control of 26 states to full control of 21 states; and 15 states would have split control, as compared to 16 currently.

That brings us to the U.S. House of Representatives, which is the hardest body to forecast. It really comes down to whether one believes the Democrats will continue to overperform as they have in special and off-year elections since 2016, and how much Republican gerrymandering will blunt any wave. Working from east to west, here is where I see changes:

  • New York: Democrats net 4 seats.
  • New Jersey: Democrats net 4 seats.
  • Pennsylvania: Democrats net 3 seats.
  • Virginia: Democrats net 3 seats.
  • North Carolina: Democrats net 1 seat.
  • Florida: Democrats net 3 seats.
  • Kentucky: Democrats net 1 seat.
  • Ohio: Democrats net 1 seat.
  • Michigan: Democrats net 4 seats.
  • Illinois: Democrats net 2 seats.
  • Iowa: Democrats net 2 seats.
  • Kansas: Democrats net 2 seats.
  • Texas: Democrats net 2 seats.
  • New Mexico: Democrats net 1 seat.
  • Colorado: Democrats net 1 seat.
  • Arizona: Democrats net 1 seat.
  • Utah: Democrats net 1 seat.
  • Washington: Democrats net 2 seats.
  • California: Democrats net 5 seats.

Going on the state-by-state, race-by-race calls, that puts Democrats at +43, giving them a 238-197 majority in the House.

However, keep in mind that this is an EXTREMELY conservative estimate. I have left a lot of potential Democratic pickups in the Republican column. If Tuesday night is really good for the Democrats, the number of gains could surpass 50. That said, one has to keep in mind the impact of Republican gerrymandering and the fact that even a wave leaves some survivors in the party on the wrong end of the wave. On the flip side, there are always some districts that surprise everybody. To wit: Don Young could lose in Alaska and somebody like Elise Stefanik could get taken out in New York. On the whole, I feel pretty comfortable predicting Democrats +43 in the House. A lot would have to go right for them on Tuesday to exceed that number.

My past results in Congressional elections, dating back to 2006, are within 1.5 seats in the Senate and 4.5 seats in the House. Using my own error margins, that could mean anything from a 51-49 Democratic majority to a 53-47 Republican majority in the Senate, and anything from a 233-202 Democratic House majority to 243-192.