House Speaker Paul Ryan appears likely to win a 10th term ahead of his primary challenge Tuesday, but an endorsement earlier this week from GOP presidential nominee Donald Trump is causing its share of political headwinds for the Wisconsin congressman and other Republicans seeking reelection.

Trump on Friday night endorsed the House leader, along with incumbent GOP Sens. Kelly Ayotte, New Hampshire, and John McCain, Arizona, in an apparent effort to create party unity with the general election less than 100 days away.

However, the endorsement is not without some peril for Ryan, despite leading primary rival and conservative businessman Paul Nehlen by as much as 66 percent points, according to poll released this week by the Remington Research Group.

The Wisconsin GOP primary is Tuesday.

Trump is not particularly popular among Wisconsin voters, considering they decisively backed Texas Sen. Ted Cruz in the state’s early-April primary, arguably Trump’s biggest loss of the season.

And weeks earlier, Trump bashed popular Wisconsin GOP Gov. Scott Walker, a Cruz supporter, arguing Walker’s record on jobs and the economy was overrated.

Nehlen, in a narrowly crafted announcement Friday, praised Trump for endorsing Ryan, saying the decision was “appropriate” and a sign of “true leadership.”  

However, he also argued Trump’s delay in endorsing Ryan, like Ryan did earlier with Trump, “is a clear signal to Wisconsin voters that Ryan is not his preferred candidate in this race.” 

Still, most political observers think Ryan will retain his seat.

“I don’t think it will be a problem for Ryan,” Republican strategist Rob Carter said Saturday. “People in his district know him and see him as a straight shooter.”

However, he argued the bigger issue is Trump’s decision to withhold the endorsement.

“The real story is the divisiveness of the Trump campaign and the selfishness of the candidate himself,” Carter said.

The Nehlen campaign -- which is hitting Ryan on his qualified support of the Obama administration’s international trade deal known as the Trans-Pacific Partnership -- thinks its candidate can still pull off an upset.

Campaign official Noel Fritsch on Saturday called the Remington poll a “farce” and argued that 83 percent of the GOP electorate voted for so-called “outsider” candidates in the 2016 party primaries.

“It’s quite obvious that establishment Republicans are in trouble,” said Fritsch, who argues that campaign contributions are coming in from across the country. “This just steels folks’ resolve to get out and vote.”

To be sure, several Republican senators in tough reelection bids, particularly in Democrat-leaning states, have struggled with the Trump endorsement.

Ayotte has said she will vote for Trump but has yet to officially endorse him. 

Despite endorsing Ryan, Trump on Monday used his Twitter feed to acknowledge support from Nehlen, who is driving around Wisconsin in a yellow dump truck with a sign that reads “Dump Paul Ryan.”

A Ryan aide said Saturday that the speaker "appreciates" Trump's endorsement and that Ryan will "continue to focus on earning the endorsement of the voters in southern Wisconsin."

Ryan supporters also argued that several polls show Ryan with a double-digit lead.

Those who foresee a potential upset point to Tea Party-backed, first-time candidate Dave Brat’s 2004 primary upset of House Majority Leader Rep. Eric Cantor, who lost in large part because voters thought he was more focused on national politics than district concerns.

“This is not and should not be considered the 'Eric Cantor' seat of 2016. Above all else, Speaker Ryan has been a consistent and effective advocate for his constituents for years. And I am sure he will continue to do so well into the future,"  Republican strategist  Rob Burgess said Saturday.