Political endorsements are pouring in, but do they really matter?

It's only a week until Minnesota's primary elections, and that means one thing: Political endorsements are about to come pouring in.

We've already seen it a few times on both the statewide and national levels. Mike McFadden got the endorsement from the national powerhouse U.S. Chamber of Commerce, but he was denied by the Star Tribune, who instead gave their blessing to challenger Jim Abeler. The Minnesota Gun Owners PAC spent yesterday handing out a huge range of endorsements, from incumbent AG Lori Swanson to five different gubernatorial candidates.

See also: Star Tribune ruffles feathers by not endorsing Mike McFadden in primary election

Considering the coverage that every single endorsement seems to get, you'd think that they make a difference. But to figure out if they actually mean anything, you've got to look at circumstances.

Kathryn Pearson, a political science professor at the U of M, says that endorsements are pretty much only important in smaller races, and even then, it depends. For those races, where the voters are less informed, an endorsement from a respected newspaper can certainly help, especially if it's a paper a voter trusts. An endorsement from a small-interest group (like an environmental or gun rights group) can also help, though it's got to be big enough in order for anyone to notice.

"For small groups without a lot of resources and without a lot of reach, the value is if the candidate can get that endorsement out there," Pearson says. "If they've got that power, then it can help."

But in bigger elections, Pearon says, where a lot is already known about both candidates, endorsements won't mean too much. A 2004 report from the American Journalism Review interviewed a number of newspaper editors and looked at a few case studies, and nearly all came back with the same result: "The impact of endorsements on national or even regional elections -- contests in which candidates are well-known among voters -- is negligible." So McFadden probably shouldn't be sweating over getting denied by the Strib.

McFadden's U.S. Chamber of Commerce endorsement, on the other hand, looks pretty good, especially from a money perspective. The Chamber is loaded with cash. The group has spent nearly $15 million already this cycle. And in 2012, it spent more than double that. The Chamber also tends to put most of its money in tight, competitive Senate races, like the 2012 race between Tim Kaine and George Allen, where it spent nearly $4.3 million. McFadden almost certainly won't see that kind of cash, but it shows that if the Chamber chooses, it can play a big role.

Send your story tips to the author, Robbie Feinberg. Follow him on Twitter @robbiefeinberg.