Rep. Tony Gonzales will face another round in his Republican primary after he was pulled into a runoff in Texas, NBC News projects, following a campaign shaped by allegations that he had an affair with a staffer in his congressional office who died by suicide last year.

Brandon Herrera, a pro-gun activist, advanced to a one-on-one runoff against Gonzales for the Republican nomination after no one in the primary got a majority. Herrera forced Gonzales to a runoff in 2024, in his first bid for office, but fell just a few hundred votes of toppling him.

While Gonzales had an endorsement from President Donald Trump this time to help him hang on to his seat, his political standing took a major hit after the affair allegation resurfaced last month.

Gonzales had denied having an affair with the former staffer, Regina Santos-Aviles. But the allegations drew new attention after Santos-Aviles’ widower publicly accused Gonzales. News organizations, including NBC News, reported that Gonzales had sent sexual text messages to Santos-Aviles.

Gonzales has not addressed the substance of the allegation since it resurfaced, and his office did not respond to repeated questions about whether he stands by his previous denials. Instead, he has accused Herrera of stoking the allegations, which he has claimed are politically motivated, and accused Santos-Aviles’ widower and his lawyer of blackmailing him.

Two sources familiar with the investigation told NBC News last month that the Office of Congressional Conduct has finished a probe into the alleged affair, but House rules prevented it from transmitting a report to the House Ethics Committee right before an election.

Gonzales, a former naval officer, was first elected in 2020 to represent the sprawling 23rd Congressional District, which stretches more than 800 miles along the southern border. He serves on the plum House Appropriations Committee and crossed party lines on a handful of key votes — including backing a bipartisan gun safety measure after a mass shooting at an elementary school in Uvalde, Texas, in his district.

That vote and others, like backing an independent investigation into the 2021 Capitol riot and legislation protecting same-sex and interracial marriages, prompted criticism from the Texas Republican Party, as well as from conservatives like Herrera, who has said Gonzales’ voting record spurred him to run for Congress.