America may be closer to sending a sitting Senator to the White House than it has been in 48 years.

With Sen. John McCain’s (Ariz.) come-from-behind victory in New Hampshire’s Republican primary on Tuesday, and with Sen. Hillary Rodham Clinton’s (N.Y.) upset win in the Democratic primary, Senators remain among the leading contenders in both parties.

The last sitting Senator to be elected president was John F. Kennedy (D-Mass.) in 1960.

The fight for the Democratic nomination is clearly a two-person affair between Clinton and Sen. Barack Obama (Ill.), who won the Iowa caucuses last week and led every public poll leading into today’s vote. On the Republican side, McCain is one of four candidates with a plausible shot at the nomination, along with former Massachusetts Gov. Mitt Romney, former Arkansas Gov. Mike Huckabee and former New York Mayor Rudy Giuliani. McCain and Romney both are counting on strong showings in the next GOP contest in Michigan on Jan. 15. Nevada and South Carolina are the next big tests for Democrats.

— Josh Kurtz