House Speaker Paul Ryan is easily beating back a Republican primary challenger despite his reticence to endorse presumptive Republican presidential nominee Donald Trump, according to a new Washington Free Beacon poll.

The survey shows Ryan leading his GOP challenger, businessman Paul Nehlen, by 73 points, 80-7, among those who say they will vote in the Aug. 9 Republican primary in Wisconsin’s first congressional district.

Ryan leads a generic Democratic candidate by 18 points, 54-36, in a general election matchup, the survey shows. Eleven percent are undecided.

The poll comes as Ryan takes heat for his refusal to throw his weight behind Trump’s candidacy. Nehlen is an outspoken Trump supporter and has criticized Ryan for withholding his endorsement.

Republicans in the district are solidly in Trump’s camp. Seventy-two percent say they will support him in the general election, compared to just 4 percent who say they will support Clinton. Nearly a quarter are undecided.

However, Ryan’s support remains steady regardless of voters’ views of the party’s likely presidential nominee. Ryan enjoys 77 percent support among GOP primary voters with a favorable view of Trump, and 79 percent among those with an unfavorable view.

Overall, voters in the district view Trump unfavorably, but their views of Democratic presidential frontrunner Hillary Clinton are no better. Both have net favorable ratings of negative 26 points.

Ryan’s slow embrace of Trump has earned him the ire of some big names in Republican politics, most notably former Alaska governor and vice-presidential candidate Sarah Palin.

Free Beacon’s poll suggests that Palin, despite her vows to campaign for Nehlen, has not been doing the challenger any favors. She has a negative 44 net favorable rating in the district, with nearly half expressing a "very unfavorable" view.

Ryan’s lead in the district has increased since earlier this month, when a Remington Research Group poll showed him leading Nehlen by 64 points, 78-14.

Ryan is viewed favorably by 76 percent of Republicans in his district, according to Free Beacon’s survey. Just 15 percent view him unfavorably.

Vox Populi Polling conducted the survey on May 22 and 23 using a mix of robocalls and cell phone interviews. Its margin of error is 2.83 percentage points.

"It’s remarkable how well positioned Speaker Ryan is for re-election this year," wrote Vox Populi’s Michael Meyers in a statement on the survey results.

"Looking at the results it is clear that Ryan’s opponent is not mounting a credible primary challenge and in the general election Ryan’s numbers are incredibly strong."

Read the full survey crosstabs here.