WASHINGTON — President Biden said Wednesday that voters should “elect me, I’m in the 20th century” — another brutal gaffe that instantly went viral among critics who say he’s too old for another four-year term.

Biden, 81, made the statement at the conclusion of a joint press conference in the White House Rose Garden alongside Japanese Prime Minister Fumio Kishida.

“Why doesn’t everybody holler at once?” the president groused as journalists shouted questions at him, before pausing to answer several queries from reporters who had not been pre-selected by his press officers.

Peter Alexander of NBC News asked Biden to address the issue of abortion in Arizona, where the state Supreme Court ruled Tuesday that an 1864 law banning abortion from the moment of conception remains in effect, with only a narrow exception to save the life of a mother.

“Elect me,” Biden replied when asked for his reaction.

“I’m in the 20, 20th century,” said the president, who regularly attracts negative commentary for appearing confused in public or misstating significant facts.

A moment later, Biden caught himself and added, “21st century, not back then. They weren’t even a state.”

The nation’s oldest-ever president trailed off as reporters shouted additional unrelated questions.

In response to a different reporter’s question about how the war in Ukraine may end, Biden said, “The war in Ukraine comes to an end by the House leader allowing a vote [on additional military aid].”

Polls consistently show broad voter concern about Biden’s mental fitness for office. He would be 86 if he completes a full second term in 2029.

Former President Donald Trump, 77, is nearly as old as Biden, but argues that he retains his cognitive abilities better than his successor, a statement that polls indicate most Americans agree with.