A former girlfriend of U.S. Rep. Keith Ellison has accused him of domestic violence, which Ellison — a DFL candidate for Minnesota attorney general — denied on Sunday.

The alleged incident between Ellison and Karen Monahan came to light Saturday night after her son posted about it on Facebook. She then confirmed it on Twitter. Ellison responded Sunday in a statement released by his campaign: “Karen and I were in a relationship which ended in 2016, and I still care deeply for her well-being.”

He also denied dragging her off a bed, and said a video allegedly showing that does not exist because it never happened.

The allegation roils the race for attorney general, where Ellison has been viewed as the front-runner in Tuesday’s DFL primary.

A fellow DFL candidate called for a criminal investigation and a national women’s group said Ellison should withdraw and resign from Congress.

Two Ellison supporters questioned the timing of the allegations days before the primary.

A Star Tribune reporter went to Monahan’s apartment on Sunday and spoke through a call-box to a woman who said she was Karen Monahan. She said she was not ready to talk and was focused on her children and family. “This is a really difficult time,” she said.

Monahan’s son, Austin Aslim Monahan, posted that he watched a video on his mother’s computer in which Ellison could be seen dragging Monahan off a bed as he screamed profanities at her.

“This video does not exist because I never behaved in this way, and any characterization otherwise is false,” Ellison’s statement read.

On her Twitter account Saturday night, Karen Monahan defended her son’s post: “That was my son who posted it and its true. He wouldn’t lie about his own mom.”

She reiterated that statement Sunday afternoon, tweeting: “Every statement he made was true. @keithellison, you know you did that to me. I have given every opportunity to get help and heal. Even now, u r willing to say my son is lying and have me continue to leak more text and info just so others will believe him.”

Austin Monahan said in an interview Saturday night that he did not have the video that he said he saw in 2017. He stood by the veracity of his Facebook post.

“I only know what I saw and I know what’s true,” he said. “It was my job to stand up for my mother.”

Of Ellison, he said: “I have no reason to tear down this man.”

A search of court records found no reports of any incidents between Monahan and Ellison. Monahan, who is an organizer for the Sierra Club, has made numerous Twitter posts in recent weeks about being in an abusive relationship, and more broadly about the MeToo movement; but before Saturday, she never identified Ellison in those posts.

In one tweet, she said: “I was physically abused, emotional and psychological and sexually manipulated by this man. I am not the first woman he has done this to and I wasn’t the last.”

Minnesota Public Radio News reported it reviewed more than 100 texts and Twitter messages between Ellison and Monahan that she provided to the station. None included any evidence of the alleged abuse, according to the report, characterizing some as friendly and others as more combative.

Monahan on Sunday tweeted some texts between her and Ellison, one of which indicated that she did not go public when Ellison’s son was running for office. Jeremiah Ellison was elected to the Minneapolis City Council in November.

In an e-mail later, Monahan described a relationship where she said she dealt with “narcissist abuse,” including manipulation, lying and victim shaming. In the incident her son was referring to, Monahan said Ellison “tried to drag me off the bed by my legs and feet” while screaming at her the day after they had a fight.

When she told him she wanted to write about her experience in the relationship, she said Ellison tried to threaten and intimidate her.

She said she offered him restorative justice and wanted him to seek some sort of help, but he would not take her up on it. “I told him not only he deserved it, but his family and constituents deserve it as well,” she wrote.

Ellison’s ex-wife, Kim Ellison, defended him on Sunday.

“I want members of our community to know that the behavior described does not match the character of the Keith I know,” her statement said.

Ellison is one of five candidates for attorney general. The others are attorney Matt Pelikan, state Rep. Debra Hilstrom, former Ramsey County Attorney Tom Foley and former state Commerce Commissioner Mike Rothman.

“Domestic Violence is never ok,” Hilstrom wrote on Twitter. “The incidents described are troubling.”

Foley said the allegations describe criminal behavior, and law enforcement authorities should begin an immediate criminal investigation.

Ultraviolet, a women’s group, said it stands behind Monahan. “A domestic abuser does not belong in any position of power but particularly not as the top prosecutor in the State,” it said.

Leni Moore, a supporter of Ellison’s who donated to his campaign, said the allegation does not shake her backing for him and her belief that he would be a good attorney general.

“I think this is completely unfair for this to be brought up now,” said Moore.

DFL donor Vance Opperman, who supports Ellison and Rothman, said he generally discounts allegations that pop up shortly before an election, referring to them as an “August surprise.”

Ellison, an attorney first elected to Congress in 2006, has risen to national prominence in recent years as a leading spokesman for progressive causes. He unsuccessfully ran for chairman of the Democratic National Committee in 2017, subsequently accepting an appointment as the party’s deputy national chairman, which he still holds.

Staff writer Jeremy Olson contributed to this report.