Confidence that Democrats are going to sweep the House and Senate this November is as high as it's ever been. Pundits treat it as a done deal, and the polls seem to back them up.

But not everything may be as it seems.

As I previously reported, Frank Luntz, a pollster who is no fan of President Donald Trump, sees a messier picture. Voters are souring on both parties heading into the midterms, according to Luntz, but the Democrat Party is in worse shape. Its turnout advantage is only about two points. That's thin, since the party out of power usually enjoys a big edge in a president's first midterm election. Luntz told CNN on Monday that everything comes down to whether Trump's voters show up. They turned out in force when Trump was on the ballot in 2016 and 2024. In 2018 and 2022, when he wasn't, they stayed home.

That's a striking admission from someone who has never been a Trump fan. But there's another factor to consider: the historic underestimation of the GOP in the polls. It happened in Trump's first term, and if it happens again the same way, Republicans will hold the Senate.

But you don't have to take my word for it. That's CNN's Harry Enten talking.

Recommended
The Morning Briefing: The Friend of My Enemy — Iran Wants Americans to Vote for Dems Stephen Kruiser A Connecticut Jihadi in an Obama Judge’s Court Robert Spencer

Enten, CNN's chief data analyst, explained on CNN News Central Wednesday that if the polls are wrong the way they have been historically in the Midwest, the GOP holds the Senate.

"We've had really good Democratic polls coming out from Ohio, Michigan, Iowa," Enten said. "And, you know, fool me once, shame on you. Fool me four times, I just have to ask the question, could it happen again?"

Could it? In major 2024 races, Republicans beat their September polling by nine points in Iowa, six in Ohio, and five in Michigan. Democrats’ leads in those states right now are smaller than those misses.

"So, you look at this and you go, you know what, maybe we should just hold on a second here because we've seen this dance before and it was not a dance that Democrats like when the votes were actually cast and counted," Enten explained.

Recommended: Lindsay Clancy's Lawyer Has Gone Completely Nuts With This Move

Berman raised the obvious objection. Trump was on the ballot in 2024, so what happens in a year when he isn't? Enten had the answer ready.

In 2018, Trump's first midterm, the GOP outperformed its September polls by six points in Iowa, six in Ohio, and eight in Michigan. Look across 2016, 2018, 2020, and 2024, and Republicans beat their September numbers by at least five points in all three states every single time.

Then Enten laid that history over this year's Senate map. If Republicans outperform their Midwest polls the way they did in 2018 and 2024, Michigan, Ohio, and Iowa all go red. Even if Democrats could carry Texas, Georgia, North Carolina, and Alaska, we would still end up with a 50-50 Senate, with Vice President JD Vance casting the tie-breaking vote.

And does anyone really believe Texas is electing James Talarico?

"So, if history holds in terms of the GOP outperforming their September polls, well, there's a very, very strong chance that Republicans hold on the United States Senate, even if Democrats win in places they don't historically win in, like Texas," Enten said.

"In these midwestern Senate races, yes, Democrats have gotten good polls," Enten noted. "But I would just say, hold on just a brief second here because history says, you know what, it might not end for them as well as the polls currently suggest it will."

Put Luntz's warning next to Enten's data, and the picture for November looks a lot brighter for the GOP than the headlines suggest.