Something has changed in the 2026 midterm elections.
Just two months ago, CNN chief data analyst Harry Enten was warning Democrats not to get ahead of themselves.
Democrats were leading Republicans on the generic congressional ballot, but only by about four points. Enten noted that the advantage was considerably smaller than Democratic leads before the wave elections of 2006 and 2018.
His warning was simple: four points might not be enough.
Now Enten is sounding a very different alarm.
This time, it's Republicans he's warning.
“The levee has been breached,” Enten said while examining the latest numbers.
His conclusion: polling is increasingly showing the ingredients of what he described as a potential Democratic wave.
And this isn't based on one poll.
The national generic congressional ballot has moved substantially toward Democrats.
The RealClearPolitics polling average currently shows Democrats ahead by nearly nine percentage points nationally.
An Emerson College poll released days ago puts Democrats ahead 53% to 42%.
NPR/PBS News/Marist has Democrats ahead 53% to 41%.
CNN's own national polling showed Democrats ahead 49% to 41%.
The Economist/YouGov found an even larger Democratic advantage.
Different pollsters. Different methodologies.
The same general direction.
But the national numbers aren't what has Enten sounding the loudest alarm.
It's what is happening inside the districts that will actually determine control of Congress.
According to the numbers Enten presented, Trump's net approval rating in key House districts stands at minus 16 points.
For comparison, Trump was approximately eight points underwater heading into the 2018 midterms.
Democrats went on to gain 40 House seats that year and take control of the chamber.
Trump's standing in the districts Enten examined is now substantially worse.
Then there's the economy.
Only 37% of voters in those key House districts approve of Trump's handling of it, according to the numbers Enten presented.
That's potentially devastating because the economy has historically been one of Trump's strongest political issues.
National polling tells a similar story.
The latest NPR/PBS News/Marist poll found Trump's overall approval at 39%, with 59% disapproving.
The same poll found Democrats now holding advantages over Republicans on which party voters believe would better handle the economy, foreign policy and gas prices.
But perhaps the most alarming number for Republicans involves independent voters.
Marist found independents supporting Democratic congressional candidates by 57% to 32%.
That's a 25-point Democratic advantage among voters who frequently determine close elections.
And there's another number Republicans can't easily dismiss.
Forty-five percent of registered voters told Marist that their congressional vote would primarily be a vote against Trump.
Only 24% described their vote as primarily a vote for him.
That suggests something bigger may be happening than voters simply choosing between individual congressional candidates.
The 2026 midterms are increasingly becoming a referendum on Donald Trump's second presidency.
There are important reasons to be cautious.
Polls are snapshots, not election results.
The election is still weeks away.
Generic congressional polling doesn't account for individual candidates, district boundaries, turnout operations or late-breaking events.
And modern congressional maps mean even a large national Democratic advantage doesn't necessarily translate into the enormous seat swings seen in previous wave elections.
But the direction of the polling is becoming difficult to ignore.
And Enten's change in tone illustrates just how dramatically the political environment has shifted.
In July, he was telling Democrats their advantage might not be enough.
By late September, he was talking about a blue wave.
The Senate picture has also moved.
Only days ago, Enten noted that if current state polling were reflected exactly in election results, Democrats would emerge with 53 Senate seats.
He immediately cautioned that it's still September and polls are imperfect.
That's an important qualification.
Nobody knows what voters will actually do until the ballots are counted.
But elections don't suddenly become dangerous for a governing party on Election Day.
Warning signs accumulate.
Presidential approval falls.
Independent voters move.
Economic confidence deteriorates.
Competitive districts become more competitive.
Safe districts become less safe.
And national polling begins moving consistently in the same direction.
That's what Republicans are confronting now.
Whether it becomes a genuine blue wave won't be known until November.
But with weeks remaining before Election Day, the political levee Harry Enten was watching earlier this summer is showing unmistakable signs of strain.