Hillary Clinton may be running neck-and-neck with Bernie Sanders in Iowa and New Hampshire, but the former secretary of state appears to be strengthening on a national level. Clinton leads the Vermont senator 59 percent to 34 percent, according to the latest Wall Street Journal/NBC News poll. That marks an increase from the 19-point lead that Clinton enjoyed in December and comes as other polls suggest a very tight race in in the first two states of the primary contest.

Even as Clinton continues to be strong on a national level though, it also seems clear that Democrats are warming to Sanders. Four in five Democrats say they could see themselves voting for Clinton, which is pretty much how it has been since March. For Sanders though there has been a huge shift. In March, a mere 21 percent of Democrats said they would be willing to vote for the Vermont senator, but now two-thirds of party members would consider voting for him.

In a separate poll, both Clinton and Sanders easily beat Donald Trump in a hypothetical match-up, but the Vermont senator has a slight advantage. While Sanders beats Trump 54-39 percent, Clinton wins by 51-41 percent.

The latest poll was released as Clinton and Sanders prepared for the final debate before Iowa on Sunday night, with lots of speculation that the two contenders are likely to go on the offensive.