A number of gay rights activists disagree with Democratic presidential candidate Hillary Clinton's explanation of why former President Bill Clinton signed the Defense of Marriage Act (DOMA).

The Supreme Court in 2013 struck down a key provision of DOMA, which prohibited federal agencies from recognizing the legal marriages of gay and lesbian couples.

On Friday, Hillary Clinton said that her husband signed the law as a “defensive action” to prevent passage of an amendment to the U.S. Constitution which would ban gay marriage.

(Related: Hillary Clinton explains DOMA, DADT; Says they were “defensive actions.”)

On Sunday, Vermont Senator Bernie Sanders, who is also vying for the Democratic presidential nomination, challenged Clinton's remarks during an appearance on CNN's State of the Union.

“[Clinton] said that it was done as a way of being defensive, to protect gay rights,” host Jake Tapper said.

“I would not agree with that assertion,” Sanders replied. “To my mind, I think the evidence is very, very clear that that legislation was anti-gay legislation, it was playing off the fears of a lot of Americans.”

(Related: Bernie Sanders criticizes Hillary Clinton on explanation of gay marriage law DOMA.)

David Mixner, who had a public falling out with Bill Clinton over “Don't Ask, Don't Tell,” and Hilary Rosen, an out Democratic activist and known Hillary Clinton supporter, were among those backing Sanders.

“Hillary's version of DADT and DOMA is so wrong,” Mixner tweeted. “The only 'defensive posture' was for their personal politics not LGBT.”

“@BernieSanders is right,” Rosen messaged. “Note to my friends Bill and #Hillary: Pls stop saying DOMA was to prevent something worse. It wasnt, I was there.”

Rosen followed up: “@Berniesanders voted right, did virtually nothing on LGBT. @HillaryClinton not perfect but engaged, & helped a lot.”