2016 Green Party presidential nominee Jill Stein on Monday warned Democrats will lose to President Donald Trump in November if they try hiding what she described as former Vice President Joe Biden’s “cognitive decline.”

“Biden’s team won’t let him do interviews. He made 2 short teleprompter speeches in Missouri this weekend & both generated massive gaffes that went viral,” Stein, Harvard Medical School graduate, tweeted. “You can’t beat Trump by trying to hide to avoid the issue of #BidensCognitiveDecline. How is this not a massive red flag?”

On Saturday, Biden touted himself as “an O’Biden Bama Democrat” in a short speech in St. Louis.

“To all of Amy’s folks, to all of Pete’s folks, to all of Kamala’s folks… Beto’s folks, I tell you what. What a gigantic difference it’s made. We’re going to unite this party and unite this country,” said the 77-year-old. “If you want to nominate a proud Democrat, a lifelong Democrat, an O’Biden Bama Democrat, join us.”

In a Saturday tweet, Stein predicted that Democrats are in for an “agonizing 8 months” if Biden is their nominee. “Biden’s lies & record are bad enough, but the biggest risk is his obvious cognitive decline,” she wrote. “He said he’s running for Senate, confused wife & sister, forgot Obama’s name etc. This isn’t going away. If Dems close their eyes & keep pushing Joe, it’ll be an agonizing 8 months ahead.”

On one point, Stein’s claims are contradicted by the evidence somewhat. Biden did recently record an interview with MSNBC’s Lawrence O’Donnell; however, it was not a live interview.

Stein joins the growing chorus of left-wing pundits voices concerns about Biden’s mental health. Author Matt Stoller tweeted Thursday: “Democratic insiders know Biden has cognitive decline issues. They joke about it. They don’t care.” Glenn Greenwald, co-founder of The Intercept, concurred with Stoller, adding, “The steadfast insistence on the part of Dems to just pretend this isn’t true and hope it somehow goes away is a staggering exercise in self-delusion.”

Biden has garnered a collection of negative headlines in response to a series of gaffes in recent weeks. While campaigning in South Carolina, Biden declared himself a candidate for the “United States Senate.” At the start of his Super Tuesday speech in Los Angeles, Biden mixed up his wife, Dr. Jill Biden, with his younger sister, Valerie. Appearing last month at a CNN town hall event, he said deceased son Beau Biden, who served as the Attorney General of Delaware, was the U.S. Attorney General.