Thomas Massie

Rep. Thomas Massie, R-Ky., heads into the May 19 Republican primary in Kentucky's 4th Congressional District favored over Trump-backed challenger Ed Gallrein in both public polling and prediction markets, even as President Donald Trump and allied super PACs press a costly effort to oust the seven-term incumbent.

Two April surveys put Massie ahead.

A Big Data Poll survey released on April 8, conducted as part of the firm's crowdfunded Public Polling Project and not sponsored by any campaign, showed Massie leading 52.4%-47.6% after undecided voters were asked who they leaned toward.

The poll interviewed 433 likely Republican primary voters on April 3-4 and April 6-7, with an overall margin of error of plus or minus 4.0 percentage points. Subgroup margins are larger.

A Quantus Insights survey of 438 likely Republican primary voters fielded April 6-7 had Massie at 46.8% and Gallrein at 37.7%, with 14% undecided and an overall margin of error of plus or minus 4.4 percentage points.

Prediction markets show a wider edge.

Polymarket on Saturday priced Massie at 77 percent to win the GOP nomination, with Gallrein at 23% on roughly $498,000 in volume. Newsweek reported Massie at 72 percent on Kalshi as of its publication.

Trump endorsed Gallrein, a farmer and retired Navy SEAL, in October and traveled to Hebron, Kentucky, on March 11 to campaign against Massie, calling him "a disaster for our party" and "the worst person."

In March, Trump wrote on Truth Social that Massie would "go down as the WORST Republican Congressman in the long and fabled history of the United States Congress" and would "hopefully lose BIG."

The dispute followed a string of Massie votes against Trump's agenda, including the One Big Beautiful Bill Act and U.S. military strikes on Iran. Massie also led a bipartisan effort with Rep. Ro Khanna, D-Calif., to force the Justice Department to release files related to the late financier Jeffrey Epstein.

Gallrein has the backing of Rep. Andy Barr, R-Ky., and a pro-Trump super PAC, MAGA KY, which has poured millions into anti-Massie advertising.

Sen. Rand Paul, R-Ky., is supporting Massie.

The 4th District covers northeastern Kentucky, including the Cincinnati suburbs and parts of exurban Louisville, and is rated Solid Republican by the Cook Political Report, with a Cook Partisan Voter Index of R+18.

The winner of the GOP primary is expected to coast in November.