The pull of the White House has always been felt at the other end of Pennsylvania Avenue. (Has there ever been a senator who wouldn’t really rather be President?) It was John Kennedy, in 1960, who challenged the notion (embodied, at the time, by Lyndon Johnson) that a senator, if he runs for President, runs on his accomplishments as a senator. Obama took that several steps further, turning the slightness of his Senate experience into an irrelevancy—or even an advantage. In late 2006, as Obama weighed whether to run for President, a former Clinton White House colleague told me that Obama only stood to lose by sticking around—that every year he stayed in the Senate, he would sacrifice more and more of his ability to be bold, talk like a normal person, and connect with people outside Washington. The title “Senator” becomes, over time, less an honorific than an epithet. Obama understood that. Cruz, Paul, and Rubio are making the same calculations. Gillibrand and Booker might be, too, if Hillary Clinton weren’t already their party’s presumptive nominee.