Presidential candidates are often career politicians, so it's not infrequent that they hail from our legislative branch.After all, those positions comprise most of the elected positions in the federal government. However, these candidates rarely make it to the presidency: since 1913, only three presidents have emerged from the U.S. Senate, the most recent example being Barack Obama, formerly an Illinois legislator, who won the 2008 race for the White House over Arizona fellow senator John McCain.
Senators run frequently — see Rick Santorum, Joe Biden and John Edwards, to name a few — but are generally beaten by governors to the nomination, or, if they manage to make it past the primaries, to the Presidency. Before President Obama, the last senator to ever attain the title of Commander in Chief was John F. Kennedy, 48 years before Obama won his first race.
In the 2016 primaries, only three senators remain: Marco Rubio, Ted Cruz and Bernie Sanders. It remains to be seen if any of them will be able to jump the primary hurdle on the road to the presidency.