Hillary Clinton: 59 percent

Bernie Sanders: 34 percent

Martin O'Malley: 2 percent

Former Secretary of State Hillary Clinton has a 25 percent lead over Vermont Sen. Bernie Sanders in the latest NBC News/Wall Street Journal national poll of likely voters.Here's how the three-candidate race stacks up:Clinton's lead is a six-point increase over the same poll in December.Though a CBS News/New York Times poll shows Clinton with only a 7-point lead, NBC News notes that its own poll filters out people who say they are not likely to vote in the primaries and caucuses.The poll of likely voters was conducted January 9-13. The margin of error of 400 Democratic primary voters is plus-minus 4.9 percentage points.