RALEIGH, N.C. (AP) — Sen. Thom Tillis is following a simple formula for reelection in closely divided North Carolina: Stand with Donald Trump.

It seems far less complicated than his winning approach in 2014. Back then, he pleased the Republican base when he advanced tax cuts and a gay marriage ban referendum during his years as state House speaker. And he won over independent, swing voters in part by accusing Democrat Sen. Kay Hagan of being too aligned with President Barack Obama.

Now, while some vulnerable Republicans have tried to hold the polarizing president at arm's length, Tillis boasts of Trump's endorsement.

Once labeled as a business-friendly moderate, and facing questions from some about his conservative credentials, the mild-mannered, former IBM consultant has dismissed the Democrats' impeachment probe as politically motivated, backed the president's border wall and said he would give Trump the "benefit of the doubt" for now on pulling U.S. troops from Syria.

That may have immediate political benefit as he fends off a March primary challenge from a substantially self-funded candidate. But it also comes with general election risks in North Carolina, where, as in other states, fast-growing cities and suburbs have flashed warning signs for the GOP. Democratic wins Tuesday in Virginia, Kentucky and several cities suggest a suburban revolt against Trump's version of the Republican Party is growing.

Tillis' race will likely test whether Republicans who hitch their wagons to Trump early can hold on to the end.

"He needs the Trump support to have a shot in the general election, but on the other hand aligning himself too closely with Trump hurts him with moderate and independent voters," Meredith College political science professor David McLennan said.

The 2020 election, McLennan added, "is a very touchy situation for Tillis to be in."

Tillis is in the small Republican group targeted by Democrats in their push to flip four seats and seize Senate control.

Obama won the state in 2008 but it returned to Republicans four years later. Trump won it by 4 percentage points in 2016 while voters narrowly elected a Democratic governor. Democrats made statehouse gains in 2018 and almost won a Republican-leaning congressional district in September.

Tillis' campaign says several hundred thousand voters in 2020 weren't on the rolls when he narrowly defeated Hagan in 2014. The state has grown more Latino, college-educated and younger, forces that could benefit Democrats, who still have the most registered voters. But overall Democratic registrants have actually fallen in five years.

Meanwhile, unaffiliated — or independent — voters have surged and now outnumber Republicans.

Tillis and his campaign contend the race won't be all about Trump's persona, but issues and accomplishments they believe will attract both the conservative base and independents.

"Next year is going to be decided on the substance of the policies that have been implemented," he recently told The Associated Press. "I'm going to focus on the result and the positive impact that they're having, and I think that's what's going to motivate voters to actually reelect the president and reelect me."

That means focusing on things like the economy and immigration — issues that his campaign says resonate with Republican and independent voters, who historically lean to the right. North Carolina's high-tech economy is booming in metro areas. Statewide unemployment is about 4%.

Many of those voters "like that their kids are graduating from college and they have a job," said Jonathan Felts, a longtime state Republican consultant not associated with Tillis.

This strategy has been complicated by revelations about Trump's effort to persuade a foreign government to investigate his political rival. Like many Republicans, Tillis has focused on what he views as the Democrats' unfair process.

"I'm not even reviewing any one piece of testimony, because that's not a whole contextual view for me to judge things. I'm not going to follow a news story. I'm not going to follow a link. I want to follow a full body of information," Tillis said during a recent visit to Charlotte to promote legislation countering illegal immigration.

His early campaign ads feature Trump calling Tillis a "warrior" and praising other Tillis legislation about so-called "sanctuary cities." The ads are aimed at the conservative base, which is at times skeptical of Tillis.

Republican primary challenger Garland Tucker, a former investment firm CEO, has seized on immigration — and his $1.1 million in personal loans — to fuel his campaign. Tucker says Tillis hasn't lived up to promises to control spending and secure the border.

"I think Tillis wants to make it about Trump," he said. "And what we're trying to focus on is Tillis' voting record."

Conservatives uneasy with Tillis cite his brief opposition to Trump's plan to divert military spending for his U.S.-Mexico wall. In February, Tillis cited "grave concerns" about executive overreach. He later reversed himself and voted for the plan.

While many Republicans support Tillis, the episode left a mark.

"I don't like Thom Tillis, he's wishy-washy," said Diane Ezzell of Marshville, before entering a September rally featuring Trump in Fayetteville, where scattered boos greeted Tillis. "We'll vote for a conservative, but it probably won't be him."

Tillis doesn't regret the flip-flop, saying he received assurances about legislation to prevent abuses in future presidential declarations.

"I supported what the president did in terms of plussing up border security," he said. Tucker, meanwhile, has had to answer for his 2016 op-ed speaking poorly of Trump as a person while stating he'd vote for him.

Tillis' support for Trump is raising hopes among the Democratic primary field.

"He appears to be trying to save his political skin," said Cal Cunningham, who's received the official endorsement of the Democratic Senatorial Campaign Committee. "I think we will continue to see him take his cue from the White House about where he's going to stand on the issues."

Cunningham nearly matched Tillis' third-quarter fundraising, although Tillis continues to have more cash than any candidate.

Tillis strategist Paul Shumaker said Democrats will have to worry about appealing to moderate voters — particularly if their presidential nominee backs Medicare for All, college debt forgiveness and "open borders."

Those policies are "grossly out of step with unaffiliated voters in North Carolina," Shumaker said.

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Associated Press writers Alan Fram and Jonathan Drew contributed to this report.

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