Bruce Reed looks at "the fallacy that successful presidential candidates are too busy to govern" and notes that in the last 20 years, "perseverers have prospered while quitters withered. Bill Clinton won a fifth term as governor of Arkansas before launching his 1992 campaign. George W. Bush won a second term in Texas two years before running for president in 2000."
"Compare that with the dismal track record of strategic quitters. In 1986, Gary Hart chose not to run for a third Senate term and went on to meet Donna Rice. In 2004, John Edwards passed up a second Senate term and went on to meet Rielle Hunter."
"Bill Bradley's decision not to seek a fourth term in 1996 helped cost him the Democratic nomination in 2000 to Al Gore, whose slogan was 'stand and fight.' Bob Dole's spectacular resignation from the Senate after he clinched the Republican nomination in June 1996 earned his campaign a few days of good press. But when his White House bid was over, Dole no longer had the Senate job he had loved."