A former governor of South Carolina and ambassador to the United Nations who is seeking the 2024 GOP presidential nomination, Nikki Haley, is predicting that President Biden will die within five years if re-elected, due to his advanced age and the pressures of the top job, meaning Vice President Harris would be installed as president.

“I think that we can all be very clear and say with a matter of fact that if you vote for Joe Biden you really are counting on a President Harris, because the idea that he would make it until 86 years old is not something that I think is likely,” Ms. Haley told Fox News.

Mr. Biden’s age — at 80, he’s already passed the life expectancy of a typical American man — has once again become a topic of conversation in the wake of his re-election announcement, with surveys frequently finding that this is an issue with both Republicans and Democrats.

Ms. Haley came out swinging on the topic of age in her own election announcement, declaring that candidates over the age of 75 should have to take a mental fitness test to run for office — a dig against both Mr. Biden and President Trump.

Mr. Biden has responded to concerns over his age, saying at a press conference earlier this week that he “took a hard look at it before I decided to run. And I feel good.”

“And with regard to age, I can’t even say I guess how old I am. I can’t even say the number,” Mr. Biden said. “It doesn’t register with me.”

In part due to Mr. Biden’s age, Ms. Harris has been under a microscope, with some speculating she could be expected to finish out Mr. Biden’s second term if re-elected.

About 70 percent of respondents reported feeling that Mr. Biden is “too old for another term,” in a February Yahoo News/YouGov poll, with a plurality of Democratic respondents, 48 percent, agreeing with the statement.

Republicans have taken the opportunity to attack Mr. Biden’s re-election efforts by suggesting that a vote for him would be a vote for Ms. Harris in the long run.

Ms. Harris though, maintains a nearly identical approval rating to Mr. Biden, with FiveThirtyEight’s average of polls showing she has, on average, a 43 percent approval rating and a 54 percent disapproval rating. Mr. Biden, for comparison, maintains a 43 percent approval rating and a 53 percent disapproval rating.

Even though most Americans are ready to have a president who was not born in the 1940s, it appears that the 2024 election is lining up to be a 2020 rematch, with Messrs. Biden and Trump heavy favorites to win the Democratic and Republican nominations.