President Trump's unusual divisiveness inside his own party could pose extra political challenges to Republicans on the 2018 ballot.

Republican incumbents and candidates keep finding themselves in the awkward position of choosing sides — either for him or against him, with either choice risking electoral catastrophe in the midterm.

Demonstrated most recently after events in Charlottesville, Va., standing with Trump through whatever he says, does or tweets should pay dividends for Republicans with a GOP base solidly behind the president.

Crossing Trump to maintain viability in the general election, as exemplified by Sen. Jeff Flake, R-Ariz., and the president, more sensitive to disloyalty than past party leaders, is likely to aggressively retaliate, potentially turning the base against the offender.

"It certainly puts an additional challenge on a candidate as they navigate issues down the stretch of a campaign," said Republican strategist Josh Holmes, a confidant of Senate Majority Leader Mitch McConnell, R-Ky.

Thorny policy disagreements between presidents and political allies are not unusual. And much as presidents prefer robust support from within, they usually understand that defections might be necessary to win seats and maintain power.

But that's not the issue Republicans have with Trump; their policy agendas are generally in lockstep.

Rather, their disputes with the president have largely revolved around character, magnified by — but hardly limited to — Trump refusing, except under duress, to specifically call out for special condemnation the white supremacists and anti-Semites that marched in Charlottesville three weeks ago.

Episodes like that have put a brighter spotlight on Republican infighting and generating sharp rebukes fro Trump where others in his position would have let it slide (publicly, at least) as the price for success in the next election.

Trump's poor relationship with Flake is another example.

The senator trashed Trump in a just-published book for exhibiting poor character and giving the Republican Party a bad image. Yet in Congress, he votes with Trump more than 90 percent of the time and is the Republican best positioned win the Senate race in Arizona in 2018.

That hasn't stopped the president from warring with Flake on Twitter and promoting his flawed primary challenger, Kelli Ward, whose nomination over the incumbent could put a precious Senate seat in jeopardy next year.

"It's no way to govern, let alone grow majorities," said a Republican operative, who requested anonymity in order to speak candidly.

Josh Hawley, the Missouri attorney general, is the latest Republican to be swept up by the vortex of intraparty bickering triggered by Trump.

Hawley is the GOP's consensus choice to challenge Sen. Claire McCaskill, D-Mo., in the midterm, with appeal across the spectrum of the party.

But his failure to rush to Trump's defense after one of his high-profile backers wrote a scathing op-ed urging Republicans to distance themselves from the president has some Missouri conservatives grumbling, according to the Kansas City Star.

"If @HawleyMO can't denounce failed Danforth hit on @realDonaldTrump, he shouldn't run against @clairecmc. #mosen," tweeted Ed Martin, former chairman of the Missouri Republican Party.

Martin was referencing the op-ed written by Missouri Republican John C. Danforth, who served in the Senate from 1977 to 1995 and is a member of Hawley's inner circle.

"Now comes Trump," Danforth wrote in the Washington Post, "who is exactly what Republicans are not, who is exactly what we have opposed in our 160-year history. We are the party of the Union, and he is the most divisive president in our history. There hasn't been a more divisive person in national politics since George Wallace."

In a telephone interview with the Washington Examiner, Danforth conceded that Republican candidates like Hawley are bound to face unique political hurdles related to Trump — due both to what the president says and does and the backlash it generates with critics like him inside the party.

"It's going to be hard for Republicans to avoid it," Danforth said.

"It doesn't have anything to do with positions on issues, because on the issues most Republicans would agree with most, if not all, of the president's positions," he added. "It has to do with the basic question of the president's divisiveness — picking fights and setting one group against another. That's the basic problem for Republicans."

Some Republican strategists say there's an easy fix. Don't take the bait and feel compelled to comment on the president. Candidates need to focus on their campaigns and their message and not get distracted.

Certain Republican strategists also predict GOP primary voters are sophisticated enough to separate Trump and his antics, of which they're well aware, from down-ballot Republicans. They point out that several Republicans won election to Congress last year amid a muted embrace of Trump.

The key is to avoid presenting themselves as obstacles to Trump's legislative agenda. The Republican Senate candidates that had trouble last year were seen as allying themselves with the Democrats, and they suffered for it.

"I think the voters can spot the difference. Are you willing to help the Democrats, or are you disagreeing with this or that nuanced position? They're a pretty discerning bunch on that," GOP consultant Brad Todd said.