After losing a net of 40 House seats in last year’s midterms, Republicans have plenty of offensive opportunities in 2020. But winning back the majority will not be easy.

On paper, the path back to 218 may look simple for Team GOP because it winds through favorable territory. There are 31 Democrats who currently represent districts that President Donald Trump carried in 2016, and Republicans need to gain 18 or 19 seats to regain House control (depending on the outcome in North Carolina’s 9th District).

But the initial battleground of competitive races is mixed.

Our first ratings from Inside Elections find 39 vulnerable Democratic seats and 29 vulnerable Republican ones. View Roll Call’s 2020 Election Guide to view all of our ratings for the House and Senate.

Watch: What race ratings really mean and how we create them

Democrats are targeting suburban districts that saw closer-than-expected races last fall, and there’s no guarantee Trump will carry the same marginal seats he did in 2016.

Republicans are also running against history. The GOP has gained House seats in just one of the last six presidential elections — in 2004, when President George W. Bush’s job approval rating was about 10 points better than where Trump’s is now. And a similar 3-seat pickup wouldn’t be enough for a majority this time.

Republicans have gained 18 House seats or more in just one presidential election in the last 50 years. They picked up 34 seats in 1980 but still remained in the minority because their numbers were so depressed coming into that election.

[Also watch: First 2020 Senate race ratings are here]

Democrats will be looking for a repeat of 2008, when they gained 20 seats in a presidential cycle on the heels of a 31-seat pickup in the preceding midterms. But that won’t be easy considering they won much of the low-hanging fruit in 2018, and Republicans in districts Hillary Clinton carried in 2016 are down to just three — New York’s John Katko, Pennsylvania’s Brian Fitzpatrick and Texas’ Will Hurd.

It’s certainly possible the GOP bounces back by winning in districts where they lost close races last year. But some of those seats, especially suburban ones, are probably gone, at least while Trump remains at the helm of the Republican Party.

For example, Democrats knocked off strong GOP incumbents Erik Paulsen (Minnesota’s 3rd), Barbara Comstock (Virginia’s 10th), Mike Coffman (Colorado’s 6th) and Carlos Curbelo (Florida’s 26th) in November. Ahead of 2020, their districts aren’t even on our initial list of competitive seats. Open seats that Republicans lost last fall — including Florida’s 27th, Washington’s 8th and California’s 49th — are also rated Solid Democratic for now, based on how poorly Trump performed in those districts in 2016.

Of course, Republicans will have a second chance at districts where Trump is more popular. Our initial ratings show Joe Cunningham (South Carolina’s 1st), Kendra Horn (Oklahoma’s 5th), Ben McAdams (Utah’s 4th), Anthony Brindisi (New York’s 22nd), Max Rose (New York’s 11th), Lauren Underwood (Illinois’ 14th) and Cindy Axne (Iowa’s 3rd) all in Toss-up races. But the GOP will need to win virtually all of those seats to have a chance at the majority.

What’s next?

Whether it’s in those districts or elsewhere, Republicans’ success will depend on their ability to follow the Democrats’ blueprint from 2018 by recruiting their own crop of political newcomers who don’t have legislative records that could be mined for attack ads. Democrats’ ability to maintain the majority will depend, in part, on new members being able to defend two years of House votes after previously running as blank slates.

Even though Democrats are on defense in a majority of competitive seats, they might have the most powerful weapon: Trump. He is unifying and energizing Democratic donors and voters better than any Democrat could. And if independents vote in 2020 like they did last year, Trump could make it difficult to win back GOP seats lost and endanger even more Republican incumbents.

But Republicans are banking on a fundamentally different election next year. Instead of a referendum on the president, like it was last year, the GOP will frame 2020 as a “choice” election against a Democratic Party of socialism, abortion bills and the Green New Deal.

It’s too early to project the focus and mood of the electorate 21 months from now. But it’s almost certain that 2020 will be an exciting cycle, complete with fights for the House, Senate and president.