He was a study in stumbles. He blamed trees for air pollution, could not remember the basics of his tax proposals, claimed to have witnessed the liberation of concentration camps, told an affecting story of World War II heroism that was in fact a scene from a movie. And this track record was so devastating that in November 1980, he won 44 states and 489 electoral votes against an incumbent president.

Joe Biden might take comfort from Ronald Reagan’s invulnerability as he contends with political reporters who have made his slips of the tongue and memory a near-daily story. No, he wasn’t vice president when he met with survivors of the Parkland shooting; yes, he confused former Prime Minister Teresa May with Margaret Thatcher; no, the shootings he talked about did not happen in Houston and Michigan; yes, he conflated several different medals ceremonies into one moving, inaccurate account. Maybe all this will matter to the Democratic voters—and to the general public—as little as Reagan’s confusions and misstatements mattered 40 years ago.

So the logical question for Biden’s campaign is: Why didn’t Reagan’s stumbles matter? After all, when he ran in 1980 his age was a significant issue. At 69, Reagan was running to be the oldest president ever inaugurated (how times change!). The key for Reagan’s success was that by 1980, the Republican Party knew and embraced him as the campaign of their conservative beliefs.