The five most competitive House races in the midterms

We've identified the five most competitive House races in the country, and they're all seats held by Republicans.

• The races in Iowa, Florida, Texas, California and Maine — all considered true coin flips — will help determine whether Democrats will win control of the House in November, according to conversations with more than a dozen Republican and Democratic pollsters, strategists, analysts, and operatives.

Why it matters: The 2018 midterms battlefield is changing every week, and this list shows the uphill battle Republicans will face if they want to keep control. There are a lot of close races, but these ones are especially close, and some haven't gotten the attention that analysts say they deserve.

Here's what binds these five races together: They're the ideal place for Democrats’ blue wave to crash in 2018. They’ve kept their GOP reps over the years, but have been slowly shifting toward Democrats — as seen either in the way their district voted in the last presidential election, in the incumbent Republican's victory margin in his last re-election bid, or in the support for the Democratic candidate in this year's primaries.

• Iowa's 3rd district: It's held by Republican Rep. David Young, who Kyle Kondik of Larry Sabato's Crystal Ball calls "an accidental incumbent." He was selected to run at a convention in Iowa in 2014 after getting less than 35% of the vote in the primary. "This will be a trickier environment" than 2014 and 2016 for Republicans, Kondik says, and Democrats think Cindy Axne — who got 58% of the vote in her primary and is backed by the Democratic Congressional Campaign Committee — is a strong candidate for them.
• Florida's 26th district: It went for Clinton by 16 points in 2016 despite keeping Republican Rep. Carlos Curbelo in office for the last four years. A majority of the district's residents are Hispanic, and both Curbelo and his likely Democratic challenger, Debbie Mucarsel-Powell, have Hispanic heritage.
• Texas' 23rd district: It's considered a perpetual swing district. Republican Rep. Will Hurd only won re-election by 1.3%, and he has distanced himself from Trump. He's facing Gina Ortiz Jones, who could be the first woman to represent this district.
• California's 48th district: This is the seat held by Republican Rep. Dana Rohrabacher, who's facing uncomfortable questions about his relationship with Russia. It has been a reliably red district, but it went for Clinton in 2016, and a recent poll put Rohrabacher and Democrat Harley Rouda in a dead heat. Not only is Orange County becoming increasingly diverse, but the number of registered Republican voters has consistently declined.
• Maine's 2nd district: Republican Rep. Bruce Poliquin represents a district that has "a strong union Democratic heritage but a proud independent streak," writes Cook Political Report's Dave Wasserman. Democrats are worried about the district's conservative, working-class voters, and it hasn't ousted an incumbent in 102 years. But Poliquin's seat is now considered a coin flip because his challenger, Democratic state Rep. Jared Golden, is considered "Maine's version of Conor Lamb."

Be smart: Democrats don't need to win all of these races to take back the House, but winning some would help.

One more thing: No one we talked to could think of an incumbent House Democrat who's in trouble. (The Senate is another story.)