It is the only statewide paper in New Hampshire, so its endorsement is highly sought after. Every candidate attempts to woo the editorial board in meeting with it. Here is the video of Newt's meeting for those who have not seen it.
"A lot of candidates say they're going to improve Washington. Newt Gingrich has actually done that, and in this race he offers the best shot of doing it again," wrote the paper's publisher, Joseph W McQuaid.
Nate Silver of the New York Times ran the numbers to see how meaningful the endorsement is. He found that "On average, the candidates endorsed by The Union Leader finished with 29 percent of the vote in New Hampshire -- an 11-percentage-point improvement from the 18 percent they averaged in the polls when the endorsement was made."