Pollsters are underestimating Trump 10 years later. What might it mean for the midterms?

Results from GOP primaries in four states this month suggest pollsters may again be underestimating President Donald Trump’s influence heading into the 2026 midterms – 10 years after wildly misjudging his chances in 2016.

Primary results in Indiana, Kentucky, Louisiana and Texas showed Trump-backed candidates consistently outperforming their polling numbers, sometimes by double digits, while establishment Republicans underperformed expectations.

The trend is raising questions about whether public polling is systematically failing to capture the strength of Trump-aligned voters in Republican primaries.

The pattern first emerged in Indiana’s state Senate primaries, where Trump-backed candidates defeated six GOP incumbents who had opposed helping the president redraw congressional maps.

Some media outlets framed the races as evidence of “Trump’s call for political vengeance” and argued the president was becoming disconnected from Republican voters.

But one Trump-backed winner said voters simply wanted change.

Voters in Indiana wanted “change and they want small communities to be listened to,” former state Rep. Jeff Ellington told the Indiana Capital Chronicle while pushing back on anti-Trump media narratives.

The trend continued in Kentucky’s 4th Congressional District.

A Big Data Poll survey conducted in early April showed incumbent Rep. Thomas Massie leading challenger Ed Gallrein by 5 points. Later polling tightened the race but still projected Massie to win.

“Historically, voters under the age of 45 vote at higher rates than we currently project and early voting seems to indicate that might be the case, which would bode well for the incumbent given this race is a generational battle,” Big Data said.

Instead, Trump-backed Gallrein won the GOP primary by nearly 10 points, representing roughly a 15-point swing from the April polling to the final result, according to Fox News.

A later Quantus Insights survey conducted in May showed Gallrein leading 53% to 45% after including leaners, making it the closest pre-election estimate. Gallrein ultimately won 55% to 45%.

The polling miss in Louisiana’s Senate primary was even larger.

An Emerson College poll conducted April 30 showed Trump-backed Rep. Julia Letlow at 27%, behind John Fleming at 28%, while incumbent Sen. Bill Cassidy polled at 21%.

Letlow went on to finish first in the May 16 primary with 45% of the vote – nearly double her Emerson polling number.

Fleming finished at 28%, while Cassidy received about 25%.

Much of the 22% undecided vote in the Emerson poll appeared to break toward Letlow, a pattern similar to what later happened in Kentucky.

The same Emerson survey showed just 9% of Louisiana Republicans held an unfavorable view of Trump.

Letlow now leads Fleming 45% to 40% heading into the June 27 runoff, according to the latest Quantus Insights poll.

“Our poll below showed Letlow leading Fleming by six points in a head-to-head,” Quantus posted on social media. “That margin will almost certainly shift after her win tonight and the victory bump that follows.”

The largest polling miss came Tuesday in Texas.

Former Attorney General Ken Paxton defeated incumbent Sen. John Cornyn by 28 points, winning the Republican Senate runoff 64% to 36%.

Polling conducted in May had Paxton leading by between 3 and 12 points, far below the final margin.

Cornyn, a former Texas Supreme Court justice, Texas attorney general and four-term U.S. senator, represented the Republican establishment wing in Texas politics.

“Cornyn created his own vulnerabilities by really allowing himself to become untethered from the desires of the average grassroots Republican in Texas,” state Rep. Mitch Little, a Paxton ally, told The Texas Tribune.

The scale of Cornyn’s defeat suggested the polling miss may have reflected more than ordinary sampling error and instead pointed to broader difficulty measuring Trump-aligned voters.

Taken together, the races suggest public pollsters may be consistently undersampling or underweighting Trump supporters in Republican primaries across multiple states.

If similar biases exist in broader approval polling and generic congressional ballot surveys – numbers frequently driving Democratic midterm narratives – the political environment heading into November 2026 could favor Republicans more than current polling indicates.

Trump’s political strength continues to center on his ability to mobilize voters often missed by traditional polling and media analysis.

“He commands unmatched influence within the Republican base, exceeding even Ronald Reagan,” GOP strategist Ford O’Connell told the Washington Examiner. “He has a mandate with the Republican base to continue to push the America First agenda, and anyone who gets in his way may well pay a political price.”