That admission prompted Warren's opponent, incumbent Sen. Scott Brown (R-Mass.), to urge her at a campaign stop Thursday "to tell the truth and answer the questions."

"My mom and dad have told me a lot of things too, but it’s not accurate. You know, you have to, especially in these type of things, when you’re checking a box and you’re getting benefits that are entitled to people who need them and who historically have been discriminated upon, and you have others relying on those representations, it is a problem," Brown added.

That statement quickly drew fire from the Warren campaign, which issued a statement accusing Brown of attacking the Senate challenger's parents and arguing they should not be "fair game."

“Scott Brown’s comments about my parents are totally out of line. I resent him questioning their honesty. My mother and father are not here to defend themselves and should be off limits. Don and Pauline Herring are not fair game and Scott Brown should apologize," Warren said.

But the Brown campaign quickly dismissed Warren's call for an apology, and Warren's rebuttal seemed to gain little traction.

“This is the second time Elizabeth WarrenElizabeth Ann WarrenTrump to nominate budget official as next consumer bureau chief Sessions floats federal law that would protect states that decriminalize marijuana Bank regulator faces backlash over comments on racism MORE has made this pathetic and baseless accusation in an attempt to escape personal responsibility for spending five weeks misleading the press and the public. With so many new questions piling up, she would be wise to come clean, stop the stonewalling and tell the truth, rather than making up frivolous and false attacks against Scott Brown," said Brown spokesman Colin Reed.

Democrats have begun publicly expressing concern over the Warren campaign's handling of the issue, urging the candidate to put the story to bed.

"There has to be an answer for this at some point, something that's full and comprehensive and has some closure to it as opposed to the way it's been dragged out — like water torture," Rep. Stephen Lynch (D-Mass.) told The Hill on Friday.

"I think you just need to get it out there, lay your cards out on the table and then you can move on," he added. "But feeding a little bit of information every week or so, that's just keeping it going and it's taken on a life of its own at this point. If they want it to go away they need to address it. They can't pretend it's not there, which is the approach they've been taking thus far."

Cameron Joseph contributed to the reporting of this article.