Rep. Martha Roby (R-Ala.) meets with locals during a fish fry in Andalusia, Ala., last month while campaigning for reelection. (Mickey Welsh / Montgomery Advertiser/AP)

On Tuesday, Rep. Martha Roby (R-Ala.) could become just the second sitting member of Congress to lose her reelection primary, or one of the few incumbents forced into a runoff because she couldn’t get the majority of the vote.

Analysts say it’s all because of what she said about President Trump nearly two years ago.

“I won’t vote for him” are words that still haunt Roby. She was one of the first Republicans who retracted her support for Trump in the final days of the 2016 presidential election after an “Access Hollywood” tape caught his crude remarks about groping women. She also called on him to drop out of the race.

“I cannot look my children in the eye and justify a vote for a man who promotes and boasts about sexually assaulting women,” she said at the time.

Two years later, Roby is paying the political price for taking that stand. As she aims for a fifth term representing rural southeastern Alabama, she has four primary challengers trying to unseat her Tuesday. Republicans watching the race say she’ll probably be forced into a July runoff with one of them.

Even though Roby is one of the most conservative members in Congress, her struggles in Alabama’s 2nd Congressional District epitomize just how much the Republican Party has changed under Trump: This is Trump’s party first.

“Voters don’t forget that easily,” said Brent Buchanan, an Alabama GOP operative closely watching the race.

Roby’s political standing in her district dropped immediately after she rescinded her endorsement for Trump. Tea party activists launched a last-minute write-in candidacy against her. She ended up getting reelected with less than 50 percent of the vote against a no-name Democrat, in a district that was redrawn to elect Republicans.

Her 2018 campaign frequently points out that since going back to Washington with Trump as president, she has voted to support his agenda, which includes issues such as tax cuts and a border wall. But Roby is facing two challengers in particular who don’t want to let voters forget that she didn’t vote for Trump.

Rich Hobson managed failed Senate candidate Roy Moore’s campaign. Moore lost the special election in December to a Democrat after accusations that he pursued teenage girls when he was in his 30s. Hobson was introduced at one of his first campaign events by the same tea party activist who tried to unseat Roby in 2016 over her Trump comments.

“I know that I back up the president, I support the president, and I will continue to do that,” Hobson said.

A former Democrat is actually the most serious primary challenger to Roby. Former congressman Bobby Bright is running for the seat that Roby took from him in 2010, this time as a Republican. He’s also cozying up to conservatives to draw a contrast with Roby.

“I am a Republican, my philosophy is Republican, and I want to run this race as a Republican,” Bright told local TV station WTVY.

Alabama candidates who don’t get a majority of the vote must go to a runoff in July with the second-highest vote-getter. Republicans watching the race expect Roby to go to a runoff with Bright.

That could actually put Roby in a much stronger position than the one she’s in on Tuesday.

Her opponent may have voted for Trump, but Bright also voted for Nancy Pelosi as House speaker when he served in Congress from 2009 to 2011. That would force voters in this Montgomery-area district to weigh their loyalty to Trump over their dislike for Pelosi.

“Are people going to rather vote for someone who used to support Pelosi, or who didn’t support Trump?” asks Buchanan.

Roby is far from the only conservative lawmaker or activist who has raised questions about Trump’s character. White evangelical women in particular have noticeably soured on Trump since he won election and faced multiple affair accusations.

Roby may well go on to win a fifth term in Congress despite her very public reprimand of the president back in 2016. But her struggles to clear Tuesday’s primary present two important lessons for Republicans in Congress right now: (1) This is Trump’s party, and (2) Beware of questioning him out loud.