For all of the Republican talk about which GOP legislators are true enough to the conservative flag to deserve reelection next year, the real 2020 elections battle will come after the party primaries are over — in a general election where voters decide which party controls the Texas House.

This summer’s news about whether House leaders have a list of Republican members they wouldn’t mind replacing could, if it persists, give voters some reason to look to the Democrats.

Texas Democrats want to knock off enough Republicans in the Texas House next year to win a majority in the 2021 Legislature, which will be drawing political districts for the next 10 years. The House has 83 Republicans and 67 Democrats, so it would take nine flips to put the Democrats in control.

Last year’s election results exposed opportunities and vulnerabilities for both parties.

Look at how statewide candidates fared in each of the House’s 150 districts in the 2018 elections. Republicans won all of the statewide races by an average of 7.3 percentage points. But their district-by-district results show where the Republican brand is strong and weak. In 31 of those 150 districts, those statewide races were competitive, meaning the vote spread was under 10 percentage points: statewide Republicans won, on average, in 15 of them; Democrats in 16. In five of those districts, the statewide Republicans prevailed by 5 percentage points or less; in 8 of them, Democrats prevailed by 5 percentage points or less.

Four House members — Gina Calanni, D-Katy, and Republicans Dwayne Bohac of Houston, Angie Chen Button of Richardson and Morgan Meyer of Dallas — won in districts where their own party’s candidates, on average, were losing the races at the top of the ballot. Another Republican — Sarah Davis of West University Place — is even further out on the plank; she represents a district that statewide Democrats carried by an average of 9.8 percentage points.

The broadest list of prospective flips — those 31 seats where top-of-ballot results in 2018 were closer than 10 percentage points — include 18 held by Republicans and 13 held by Democrats. Another list useful for political plotters is candidate-specific: Who won a close race in 2018? A win is a win, of course, but a narrow win is an invitation to either a rematch or a new challenge. And several House members face that risk.

A total 46 candidates — 17 Republicans and 29 Democrats — were elected to the Texas House without opposition in 2018.

Another 77 members — 49 Republicans and 28 Democrats — were elected by margins bigger than 10 percent.

The remaining 27 members — 17 Republicans and 10 Democrats — won by fewer than 10 percentage points; 14 of those — eight Republicans and six Democrats — won by margins of less than 5 percentage points.

And who in the Legislature barely made it past voters last time, winning by less than 3 percentage points? Two Democrats, both of them new to the Legislature: Calanni (also on the other high-risk list) and Michelle Beckley of Carrollton, both of whom beat Republican incumbents last year. Four more Democrats — Vikki Goodwin, Jon Rosenthal, James Talarico and Erin Zwiener — rode in on margins of less than 5 percentage points.

Six Republicans count as barelies, including Bohac, Button and Meyer from the other list, and Matt Shaheen and Jeff Leach of Plano, and Jonathan Stickland of Bedford, who this year announced he won’t seek another term in the House. Republican Reps. Bill Zedler of Arlington and Rick Miller of Sugar Land each won by less than 5 percentage points.

Republicans outnumber Democrats in high-risk districts, either way you look at 2018’s results. That election doesn’t predict what will happen in 2020, any more than the 2016 results foreshadowed 2018. It does, however, give everyone — candidates, consultants, donors and voters — a map to some of the weak spots on each party’s general election ticket.

Some incumbents in both parties will fall victim to challengers in the primaries; they always do. That’s of interest to the party animals, and in particular, to party animals in the Texas House. But most of the outside interest is not in which Republicans fill the GOP seats in the House, but in which party has the majority there when Texas redraws its political districts starting in January 2021.

— Ross Ramsey is a co-founder of The Texas Tribune.