Virginia's Gov. Ralph Northam is facing calls for his resignation as pressure mounts over a racist photograph that appeared under his name in an old medical school yearbook.

On Saturday, the Democrat vowed to remain in office during a news conference from the Governor's Mansion after a turbulent 24-hours. The photograph on Northam's page of his 1984 Eastern Virginia Medical School yearbook shows what appears to be a man in blackface standing alongside another person dressed in a Ku Klux Klan cloak and hood.

Northam on Friday apologized for the photo in a video posted to Twitter, saying he could not "undo the harm my behavior caused then and today," but by Saturday he had shifted course.

Ralph Northams page in the 1984 yearbook of Eastern Virginia Medical School has a photo of a man in blackface and another man in a Klu Klux Klan costume. (Obtained by The Washington Post via Getty Images)

"That photo and the racist and offensive attitudes it represents does not reflect that person I am today or the way that I have conducted myself as a soldier, a doctor and a public servant. I'm deeply sorry," he said in the Friday message. "I cannot change the decisions I made, nor can I undo the harm my behavior caused then and today. But I accept responsibility for my past actions and I'm ready to do the hard work of regaining your trust."

The following day, Northam said he was not in the picture at all.

"It has taken time for me to make sure that it's not me, but I am convinced, I am convinced that I am not in that picture," he told reporters during his news conference on the report, according to The Associated Press.

Northam told reporters he had darkened his skin before. In that instance, Northam said he once applied shoe polish to his face as part of a Michael Jackson costume for a dance contest in 1984 when he was in the U.S. Army. Northam said he regrets he didn't understand "the harmful legacy of an action like that," the AP reports.

Virginia has long battled a legacy of violence and racism, and the allegation against Northam is the latest in a national dialogue on race and power. Just last week, Florida's secretary of state resigned after photos surfaced from a 2005 Halloween party that depicted him in blackface dressed as a Hurricane Katrina victim.

Patrick Howley – editor in chief of Big League Politics, who first reported the existence of the photo on Northam's yearbook page on Friday – told The Washington Post he was tipped off by "a concerned citizen, not a political opponent," a claim that has drawn skepticism in light of the site's reported Republican backing. Still, the development triggered a swift political backlash, with groups on the state and federal level calling for Northam to step down.

Both of Virginia's U.S. senators, Mark Warner and Tim Kaine, said they no longer believe Northam can effectively serve as governor, and the Virginia Democratic Party and the Virginia Legislative Black Caucus have called for his resignation.

"The damage that has been done by these revelations is irreparable," the caucus said in an updated statement released Saturday. "Our confidence in his ability to govern for the over 8 million Virginians has been eviscerated."

President Donald Trump, who supported Northam's Republican opponent in 2017, also weighed in on Twitter, calling Northam's actions related to the photo and his recent stance on abortion "unforgivable!"