In 1957, when President Dwight Eisenhower suffered a stroke, Vice President Richard Nixon almost assumed the presidency, according to the book, "Ike and Dick: Portrait of a Strange Political Marriage," by Jeffrey Frank.
Thomas Mallon, writing in The New Yorker on Nixon's 100th birthday, speculates:
"Nixon would have reached the Presidency a dozen years sooner, at the age of forty-four. He would have arrived in the Oval Office misshapen by politics, to be sure, as a bruising campaigner who’d been forced to balance his checkbook on live TV and then spend five years trying to figure out the ways of a maddening boss whom everybody else seemed to love. But he would not have undergone the psychological damage of two crushing defeats that still lay ahead, and he would not have been presiding over a country at war in Southeast Asia and with itself. If that had happened, who knows what this gifted, knotted-up man, this “one of us,” might have spared himself, and his wife, and every other one of us?" --"Wag the Dog: The Making of Richard Nixon."