HUNTSVILLE, Ala. — Alabama Republicans have a choice between a Trump-like outsider and a Trump-backed insider Tuesday in a closely watched Senate GOP runoff that has the potential to wreak havoc on the Senate Republicans’ narrow majority.
In a fitting conclusion to a sometimes nasty battle, supporters of GOP establishment-backed interim Sen. Luther Strange, R-Ala., are expected to rally on the eve of the election with Vice President Mike Pence. On the other side of the state, backers of insurgent candidate Roy Moore will stump with Trump’s former chief strategist, Steve Bannon, and controversial "Duck Dynasty" star Phil Robertson.
Trump is taking a risk backing Strange, whom he campaigned for Friday night here, but many see far more upside potential for the president than downside. If Strange wins, Trump will be credited for turning the tide, engineering an upset, and saving an incumbent — earning goodwill with GOP lawmakers.
If Moore prevails, Trump will be dinged for falling short in pulling his candidate across the line. But at the same time, it will be read as a sign of anti-GOP establishment strength, a movement acting in Trump's name, regardless of his endorsement in this race. The president still remains perhaps their best and only hope in D.C. for change.
His support for Strange, as the president has made explicit, is about personal loyalty to him, not about ideology.
Trump, who has flirted with endorsing primary challenges to incumbent Republicans and regularly vents his frustration with Senate Majority Leader Mitch McConnell, seems comfortable emboldening, or at least not squashing, Bannon-ite primaries.
And Moore backers, who can't bring themselves to believe Trump really means it with Strange, would be eager to have the president back on their side.
"He once again put himself in a 'heads I win, tails you lose' situation," said Steven Law, president of the Senate Leadership Fund, a super PAC tied to McConnell that has spent $8 million backing Strange.
Moore, a well known and controversial former chief justice of the state Supreme Court, won the first round of the two-stage Republican primary, but polls show Strange narrowing the gap in recent days.
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Trump packed an arena here Friday night to give a full-throated endorsement of Strange. But the president also was quick to say he’d be fine with Moore, too.
"I’ll be honest, I might have made a mistake," Trump joked of backing Strange. "If his opponent wins, I’m going to be here campaigning like hell for him" against the Democratic candidate in the December general election.
While most national Democrats have yet to discover the race, Vice President Joe Biden will visit Alabama next week for the party’s nominee in the December 12 contest, Doug Jones, a former U.S. Attorney who prosecuted Birmingham's 16th Street Baptist Street bombers.
Many of Trump's most prominent supporters — including several former advisers and one of his cabinet secretaries, Ben Carson — have lined up behind Moore, insisting that he is the rightful tribune of Trump's populist movement. At the rally in Montgomery Thursday, a parade of speakers took to the mic to praise Trump and assure voters that, no matter what the president said, voting for Moore is the only way to continue what Trump started.
"He wants so badly to help America be great again, to get back on track again, and sometimes he gets bad advice," said Rep. Louie Gohmert, R-Texas.
Sebastian Gorka, Trump's former counter-terrorism adviser, reminded voters of their stunning victory in November before warning about this race, "Just think who you have on the other side — a man endorsed by Mitch McConnell!"
The crowd booed as Gorka conveniently failed to mention who else was supporting Strange.
"A vote for Judge Moore isn't a vote against the president," former Alaska Gov. Sarah Palin said at the event. "It's a vote for the people's agenda that elected the president.
The stakes are higher for McConnell, who could face one of the worst weeks of his tenure if both this election and the imperiled effort to repeal the Affordable Care Act go south.
He would see the loyal Strange replaced with someone who has railed against McConnell on the stump and vowed to fight him in Washington.
While 83 percent of Republicans nationally approve of Trump, there are more Republicans who have a negative view of McConnell (25 percent) than a positive one (17 percent), according to an NBC News/Wall Street Journal poll.
Chu Green drove three hours to sit in the front row of the Moore rally and hold a sign: "Mr. President and Mr. V.P. I love you, but you are WRONG." She said she’d forgive this one lapse in judgment nonetheless.
The loss of an incumbent senator to a far-right challenger also would send chills through the spines of other Senate Republicans facing their own primaries in the 2018 midterm elections.
But Rob Engstrom, political director of the U.S. Chamber of Commerce, which has spent seven figures backing Strange, predicted a win on Tuesday, dismissing Moore as a "self-appointed fake conservative."
Democrats are watching closely too, hoping destructive GOP primaries could help them overcome an unfavorable map.
"The Republican primaries raging across the Senate map will drain resources from the GOP, damage their eventual nominee and exacerbate the fissures within their party," said David Bergstein, a spokesperson for the Democratic Senatorial Campaign Committee.
Moore, who says high murder rates are God's punishment for America's acceptance of "sodomy," is a central-casting villain for Democrats, who could raise millions off his bombastic quotes.
Senate Republicans know he has no problem making enemies out of friends. As a strict military policeman during the Vietnam War, he took to sleeping surrounded by sandbags out of fear of an attempt on his life, according to his memoir.
"I did not consort with the troops," he wrote. "A boxing ring was constructed, and I took on all challengers. I won all of my fights."
Strange, meanwhile, is a back-slapping former corporate lobbyist with deep ties to the Alabama business community, but limited recognition beyond that.
At the University of Alabama's home-opener football game against Fresno State earlier this month, one Alabama politico was stunned to see Strange schmoozing with boosters and VIPs at a private pre-game party, rather than pressing the flesh with the fans tailgating outside.
But he’s hugged Trump close and is counting on the president to deliver.
"My opponent says the president is out of touch with his base," Strange said at Friday's rally. "It doesn’t look like that to me."
Alex Seitz-Wald is senior digital politics reporter for NBC News.