Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

ST. PAUL, Minn. — An ex-girlfriend's allegation that Minnesota Rep. Keith Ellison once physically abused her could not be substantiated because she refused to provide video she said she had of the incident, an attorney hired to investigate the claims concluded in a draft report obtained Monday by The Associated Press.

The report was compiled by Susan Ellingstad, a lawyer hired by Minnesota's Democratic-Farmer-Labor Party to investigate the allegation against Ellison. The Democratic congressman has denied the allegations.

Karen Monahan alleged in August that Ellison dragged her off a bed by her feet while screaming obscenities at her in 2016. Monahan said she had video footage of the incident and levied the allegation just days ahead of a crowded Democratic primary for Minnesota attorney general that Ellison went on to win.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

The state's Democratic party launched an investigation into the allegation, retaining a local attorney with links to the state party to determine whether the alleged incident took place. Democratic party chairman Ken Martin said last week he expected the investigation to conclude soon.

A draft report obtained by the AP notes Monahan's shifting rationale for refusing to produce the video footage, including that it was lost, was on a USB drive in storage and that it would be too embarrassing and traumatic to release it.

Ellingstad also wrote in her report that Monahan would not allow her to view the footage privately.

"An allegation standing alone is not necessarily sufficient to conclude that conduct occurred, particularly where the accusing party declines to produce supporting evidence that she herself asserts exists," Ellingstad wrote. "She has thus repeatedly placed the existence of the video front and center to her allegations, but then has refused to disclose it.

Ellingstad is a partner at the law firm with the state party's top attorney, Charlie Nauen. Neither Ellingstad nor Monahan immediately responded to requests for comment. The Democratic party did not immediately confirm the report's authenticity Monday.

The allegation against Ellison has loomed over his bid for attorney general and Democrats nationwide , especially as they push for answers surrounding the sexual assault allegations against Supreme Court nominee Brett Kavanaugh.

Democrats in Minnesota are concerned that the allegations against Ellison could impact their chances in November to hold onto an attorney general's office they've held for more than four decades. Public polling shows Ellison in a close race with Republican Doug Wardlow, a little-known former state lawmaker who has turned the allegations into a campaign issue.