GOP presidential candidate Newt Gingrich just snagged the endorsement of arguably the most prominent newspaper in one of the most influential primary states.

But newspaper endorsements aren’t what they used to be.

“Newspapers are in a decline, so obviously they don’t have as much clout now,” said Robert Erikson, a professor of political science at Columbia University. “They used to be more influential.”

The practice of editorial board endorsements stretches back to the dawn of American politics, but while endorsements tend to boost a presidential candidate’s poll numbers, they seem to have little effect on whether that candidate will win their party’s nomination, let alone the general election.

Take the Manchester Union Leader, the newspaper that threw its weight behind Gingrich this past weekend.

Of the six candidates the Union Leader endorsed in the Republican primary since 1980, half have gone on to win the New Hampshire primary, and two became the eventual nominee, according an analysis by the New York Times’ Nate Silver.

But while a nod of approval from the first-in-the-nation state’s most prominent newspaper does not necessarily propel candidates to electoral success, it does give them a boost in the polls.

All six of the endorsees did significantly better in the primary than they were doing in polls at the time of the endorsement, improving, on average, 11 points between the endorsement and the primary election, Silver finds in his analysis.

“Newt should get a bump out of this and it makes sense because it’s a conservative newspaper and it’s very influential with conservative voters,” Erikson said.

The Des Moines Register has an even worse endorsement to nominee record. The past three primary candidates to win the Iowa paper’s endorsement went on to lose their party’s nomination.

Florida’s Orlando Sentinel, on the other hand, has endorsed the eventual nominee in all of the past three presidential election cycles.

Neither the Register nor the Sentinel have yet to make endorsements this year.

Chris Arterton, a  political management professor at George Washington University, said the timing of the endorsement, the newspaper’s reputation and how visible the race is make a huge difference on whether an editorial board’s endorsement makes a splash or is just another drop in the bucket.

For example, when the Los Angeles Times endorsed Richard Nixon in 1972 it had a minuscule impact because the endorsement was expected. The newspaper had only ever picked Republicans.

But when the paper , after taking a 36-year hiatus from presidential endorsements following their nod to Nixon, threw its support behind Barack Obama in 2008, the California daily’s support had a much greater impact. Obama was the first Democrat endorsed by the paper in its entire 127-year history.

“It’s fair to say that in some conditions newspaper endorsements can make a major difference,” Arterton said. ”In the unique circumstance of New Hampshire I think this could be a fairly consequential endorsement.”

Arterton said that because the GOP primary has been so volatile, with a new front runner every month, an endorsement from an influential newspaper, especially one in an early primary state, could help solidify Gingrich as more than just the lastest anti-Mitt Romney Republican option.

“If Gingrich does begin to look like, let’s say, more than just the candidate of the month,” Arterton said, “I think conservative donors nationally who might have been sitting on the sidelines and not terribly comfortable with Romney may be induced by this to jump in and make contributions.”

Eric Appleman, who runs the Democracy in Action websites on presidential campaigns, said that because so many Republicans seem to still be undecided about who to support with the Iowa caucuses just over a month away, endorsements from the Union Leader, the Des Moines Register or other early primary states’ newspapers could give a candidate the staying power they need to achieve election success.

“When candidates are striving for credibility in the pre-primary period or the early primaries or seeking to persuade swing voters in the fall a newspaper endorsement may count for something,” he said.

ABC News’ Alexa Keyes contributed to this report.