Martin Heinrich

SANTA FE — U.S. Sen. Martin Heinrich was one of the first sitting Senate Democrats to endorse the campaign of Maine oyster farmer Graham Platner.

But Heinrich joined a growing number of other Democrats in rescinding his support of Platner this week, following reported allegations that Platner sexually assaulted a woman he was dating.

In a social post late Monday, Heinrich said he could no longer back Platner’s candidacy. He also called on Platner to step aside and allow another Democrat to run against incumbent U.S. Sen. Susan Collins, a Republican who has served for nearly 30 years on Capitol Hill.

“The allegations reported today are appalling,” Heinrich said in his post. “If accurate, they reveal conduct that is completely unacceptable and incompatible with the integrity we should demand from those seeking public office.”

Heinrich initially endorsed Platner in March, saying the former U.S. Marine was “focused on delivering for Mainers,” not billionaire donors. In addition, a political committee affiliated with Heinrich made a $5,000 donation to Platner’s campaign in May, according to Federal Election Commission records.

Up until this week, Heinrich had defended Platner amid scrutiny about the candidate’s record, saying in an October 2025 interview that Platner had evolved and learned from his past mistakes.

Heinrich has become a frequent endorser in New Mexico races in recent years, though he did not endorse Democratic gubernatorial nominee Deb Haaland until after the June 2 primary election. Heinrich had previously considered running for governor but announced in January he had decided against doing so.

Meanwhile, New Mexico’s other U.S. senator, fellow Democrat Ben Ray Luján, has taken a more measured approach to the U.S. Senate race in Maine, which is one of the nation’s most closely-watched contests.

Luján, who is seeking reelection this year, also weighed in on the latest allegations against Platner, saying late Monday that he should withdraw from the Senate race.

“The American people deserve leaders they can trust,” Luján said. “These allegations are serious, demand accountability and make that trust impossible.”

As of Tuesday, Platner had not announced whether he plans to heed the calls to drop out of the race. He denied the allegations against him in a social media video, but said he was taking the time to reflect on the best path forward.

Republicans hold a narrow 53-45 majority in the U.S. Senate, though two independent senators — Bernie Sanders of Vermont and Angus King of Maine — regularly caucus with Democrats.

Given that backdrop, Democrats have eyed this year’s race in Maine as a top pick-up opportunity, along with contests in North Carolina, Ohio and Texas.

Dan Boyd covers state government and politics for the Journal in Santa Fe. Follow him on X at @DanBoydNM or reach him via email at [email protected].