A group of conspiracy-minded conservatives have been increasingly pushing the theory that Democratic presidential nominee Hillary Clinton is hiding a serious physical or mental ailment from the American people.

They have an ally in Republican presidential nominee Donald Trump, who took a jab at Clinton’s “mental and physical stamina” during a speech on Monday.

“Hillary Clinton lacks the judgment, as said by Bernie Sanders, stability, and temperament and the moral character to lead our nation,” he said in Youngstown, Ohio. “Importantly, she also lacks the mental and physical stamina to take on ISIS and and all of the many adversaries we face, not only in terrorism but in trade and every other challenge we must confront to turn our great country around.”

His coded language comes amid growing insistence from some conservatives that Clinton is unhealthy, and years of suggestions that she is too old or otherwise physically incapable of being president. (Trump, it should be noted, is two years older than Clinton.)

Fox News host Sean Hannity devoted several shows last week to an “investigation” into Clinton’s health. Multiple conservative news sites, boosted by the Drudge Report, have also claimed she is in questionable health.

Their latest evidence: photos of Clinton being helped up some stairs and a video of her shaking her head that, according to them, may show her having a seizure. Neither of those theories hold up to scrutiny. The stair photos are from February, and show Clinton being steadied after slipping. In the video from June, she is making an exaggerated motion in jest while reporters ask her questions. The National Enquirer claimed recently that Clinton gained 103 pounds ― something that would be tough to hide given the number of public appearances she makes.

This has been going on for years. People Magazine featured a photo of Clinton holding onto a chair in 2014, prompting the Drudge Report and others to speculate that she used a walker ― despite there being plenty of evidence to the contrary.

Clinton suffered a concussion and blood clot in 2012, but her physician wrote last year that she was in “excellent physical condition,” and was diagnosed with only seasonal pollen allergies and hypothyroidism. Trump, for his part, released a short letter from his doctor in 2015 stating that he would “be the healthiest individual ever elected to the presidency” if elected.

Nothing has stopped Trump from claiming or hinting that Clinton has physical problems. He said in July that she takes four- to five-hour naps, whereas he does not ("We don’t have time!”).

“How do you think ISIS is going to react?” Trump said then. “We don’t need someone who goes home and takes naps.”

His accusation got even more grim this month.

“She took a short-circuit in the brain,” Trump said at a rally. “She’s got problems. Honestly, I don’t think she’s all there.”

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims ― 1.6 billion members of an entire religion ― from entering the U.S.