WASHINGTON (TNS) — In Washington, President Donald Trump struggles with record-low approval ratings — but 80 percent of Republicans rate him highly.

In Montana, Republican Greg Gianforte assaulted a reporter before a special congressional election, but he triumphed anyway, with Trump hailing his "great win."

And in Alabama, failed Republican Senate candidate Roy Moore was accused of child molestation, but 91 percent of Republican voters still backed him, as did Trump himself.

The tensions between a Republican base unshakably committed to the Trump party line and a broader populace that is becoming ever more disillusioned have some conservatives worried about what Trumpian tribalism means electorally and to the soul of their party as the 2018 election year opens.

"It's not about ideology anymore. It's about loyalty to the president," Rep. Charlie Dent, a retiring Pennsylvania Republican, said Sunday on ABC's "This Week." "Now the litmus test has changed. The issue is loyalty to the man, to the president."

Activists on both sides of the ideological spectrum in 2017 settled into the habit of assessing nearly every policy and political issue through the charged, often emotional lens of whether it would help or hurt Trump and everything he represents.

The 2016 presidential campaign laid the groundwork for this explosive climate, drawing the battle lines over race, class, and –– according to Trump's critics –– basic decency. New Republican splits emerged in the party's civil war over whether party affiliation was reason enough to overlook the uniquely serious misgivings some had about their party's candidate.

Ultimately, for most Republicans, the answer to that question was yes, for reasons including concern for the Supreme Court, economic interests and distaste for the Democrats.

And in special elections since then, culminating in Alabama last month, "yes" has continued to be the answer. Moore won Trump's blessing, and Republicans rallied around a man accused of preying on children, who was so flawed that the party lost what should have been an easy election.

"To think about how many on the Christian right, the Trumpist right and elements of the Trumpist media actually supported Roy Moore despite all the things he's said and done is truly amazing," said Charlie Sykes, who was a conservative radio host in Wisconsin and is now a Trump critic and the author of the recent book, "How the Right Lost its Mind." "It can't be explained in any other way than as a sign of extreme tribalism."

That backdrop creates concrete challenges for Republican lawmakers now, as the 2018 congressional election cycle begins in earnest. Polls show that many Republican candidates can't afford to alienate their base by being perceived as breaking with Trump or hurting his cause. But in key races that will determine control of Congress, candidates have to appeal to independents as Trump's popularity remains at historic lows.

Meanwhile, the kinds of issues on which voters and lawmakers have had to take sides last year have often turned into charged debates over the morality and character of individuals –– and of the political parties themselves. Partisanship tests have been pushed to new limits with allegations of sexual assault against lawmakers in both parties, and questions of White House racial sensitivities after the deadly white supremacist rally in Charlottesville, Va.

"The more we've gotten away from basing decisions, politically, on whether or not this is something we find morally and personally tenable, the more we've devolved into this miasma of factionalism, of partisanship," said former Ohio Republican Chairman Matt Borges, who clashed with Trump during the campaign. "It really comes down to a matter of personal tolerance. Are you able to, at some point in time, point to something and say that's fundamentally wrong? Call it for what it is? ... Can you look at the other side and say, 'I applaud them for doing something right'?

"There doesn't seem to be any appetite to do that either".

Sharp partisanship and willingness to hold the opposing party to a different standard is not limited to one side.

The progressive base, enraged by Trump's election, has activated, making hard-line demands for Trump's impeachment and threatening major pushback on Democratic lawmakers who might have otherwise worked with Republican colleagues on issues like taxes.

"It's both parties," said Republican strategist Jon Seaton. "You can't get one Democratic vote in either house on the tax bill, so it's not just our side. The country is really hunkered down; everyone's gone to their respective corners. And so while maybe there's some hope (now) that Roy Moore didn't win, I still think tribalism is something we're definitely going to be dealing with in the short term."

As 2017 wound down, some conservatives worried about that phenomenon in the Republican Party found reason for optimism in Moore's loss, the last major race of the year. After all, even though he won support from Trump and from the vast majority of Republicans who voted, there were also plenty who didn't vote, some who crossed party lines, and others who wrote in another person's name.

"But for tribalism, Moore wouldn't have been close," said conservative writer David French, who was a leader of the Never Trump movement during the presidential campaign. "But tribalism was not omnipotent here. The bottom line is Moore lost a race that was virtually impossible to lose."

French woke up after the election post feeling "more encouraged about the state of our politics," he said. But, he said, "Let's not get too optimistic.

"There is a line, for sure. "But that bar is pretty darn low."