As President Biden prepares to address the nation Wednesday evening regarding his decision to end his quest for a second term, the White House is pushing back hard at suggestions his decision was made on medical grounds.

This comes as top Republicans are demanding the president resign immediately, arguing Mr. Biden’s health problems should preclude him from serving another six months.

While the president did not give a reason for withdrawing from the campaign in his statement on Sunday, his youngest brother, Frank, told CBS News that the decision was health-related, suggesting the president’s condition is grave.

On Sunday, ABC News’s John Santucci said in a post that Frank Biden speculated that his brother’s decision to step aside “boils down” to his  “overall health and vitality,” as well as to his chances of “beating this genuine threat to our nation in the form of Donald Trump.”

“Selfishly, I will have him back to enjoy whatever time he has left,” Frank Biden told CBS News.

In a 2022 interview with the New Yorker, he recounted his history of severe alcoholism, including spending multiple stints in rehab and undergoing the most severe form of withdrawal, known as delirium tremens, which can be life-threatening. He says he’s been sober for 25 years.

Republicans are focusing on President Biden after his decision to bow out of the presidential race, even as Mr. Biden emerges from his Covid isolation in Delaware to address the nation. His speech will be watched carefully for how he describes his decision not to seek a second term.

Multiple news reports said Mr. Biden’s decision came after he endured intense pressure from leading Democrats, primarily from Nancy Pelosi, the former House speaker, who shared with Mr. Biden polling data that showed his path to victory was increasingly narrow.  

Another member of the Biden family, Mr. Biden’s younger sister Valerie Biden, has also suggested that some in the family had grown concerned over the toll continued campaigning could take on his health.

Mr. Biden is vowing to finish out his term. In previewing his Oval Office address, to be made Wednesday at 8 p.m. EST, he said he will describe “what lies ahead and how I will finish the job for the American people.”

Speaker Johnson said in a post that if Mr. Biden “is not fit to run for President, he is not fit to serve as President. He must resign the office immediately.”

Congressman Tom Emmer, the no. 3 Republican in the House, said in a post that “If the Democrat party has deemed Joe Biden unfit to run for re-election, he’s certainly unfit to control our nuclear codes. Biden must step down from office immediately.” 

Congresswoman Elise Stefanik has also echoed these sentiments, saying that, in her opinion, Mr. Biden “must immediately resign.”

“If Joe Biden can’t run for re-election, he is unable and unfit to serve as President of the United States,” Ms. Stefanik said.