The first lady's steadfast support of President Biden after his heavily criticized debate performance Thursday may seem admirable to some Americans, but not all of them.

Bill Stevenson, who was married to Jill Biden from 1970 to 1975, candidly discussed his ex-wife in an interview with the New York Post Saturday.

"The Dr. Jill Biden who I’ve seen on TV in the last five years is not the same person I married or that I recognize in any way," Stevenson lamented. "She’s matriculated into a completely different woman."

On Thursday, the first lady gushed about her husband's debate performance despite immediate calls for Biden to drop out of the race.

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"Joe, you did such a great job," she told him at a debate after-party. "You answered every question. You knew all the facts."

According to Stevenson, Jill Biden's support of her husband is far from helpful.

"I just don’t understand why she is so adamant about defending him and keeping him in the race since it appears that he’s struggling," Stevenson said. "It appears that he’s struggling with everybody these days.

"I’ve been proud of her at certain moments. I have no hard feelings. … I’m just surprised to see her front and center in the middle of this battle after flying under the radar for so many years. She’s always been very driven. People say she’s the one who wants to be president now."

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Stevenson, a staunch supporter of former President Trump, also accused the sitting president of lying habitually.

"It makes me cringe every time he calls Trump a liar because I’m telling you right now, there is no better liar than President Biden," Stevenson said.

"He’s just a bad person. I’m probably one of the few people outside his family who has known him for 50 years."

Biden is facing increased public scrutiny after his appearance at the presidential debate Thursday, where he appeared frail and stumbled numerous times. On Friday, The New York Times editorial board called for the 81-year-old politician to drop out of the race.

"Biden is not the man he was four years ago," the editorial board wrote. "The president appeared on Thursday night as the shadow of a great public servant. He struggled to explain what he would accomplish in a second term. … [T]he greatest public service Mr. Biden can now perform is to announce that he will not continue to run for re-election."

The first lady's office did not immediately respond to Fox News Digital’s request for comment.