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Two new political endorsements of Republican presidential candidates made national headlines in recent days: Former Utah Gov. Jon Huntsman Jr. secured the endorsement of the Boston Globe on Thursday, one day after Sen. John McCain endorsed Mitt Romney. The Globe endorsement feels like a big deal for Huntsman, who trails in the polls and faces a make-or-break proposition in the form of Tuesday’s New Hampshire primary. But for Romney, McCain's blessing was just the latest in a long line of high-profile endorsements that is unparalleled among his fellow GOP candidates. "Hoping to bolster credibility and build political muscle, Republican presidential contenders have jockeyed for months to woo governors and congressional lawmakers, state senators and county sheriffs, newspaper editorial boards and tea party activists," the Associated Press reported last week. "The game has been dominated so far by former Massachusetts Gov. Mitt Romney, who appears to have captured more endorsements than the rest of the field combined." In a broader sense, though, the Globe and McCain endorsements provide entree to a much larger issue: How much do political endorsements really matter in the first place? To be sure, some voters may put a lot of stock in a political endorsement. But, especially when the people doing the endorsing are fellow politicians, it is sometimes difficult to measure any discernable bump in the polls arising from a particular endorsement. For example, a 2007 New York Times article quoted Rutgers University political scientist and congressional expert Ross K. Baker as saying, "The political value of an endorsement by a member of Congress is only slightly more useful than an endorsement by a candidate’s mother. People who run from Washington have an inflated view of the importance of the people they deal with in Washington. … It marks you as an insider." Some endorsements do seem to matter in certain areas, as the following list shows. What follows are illustrative examples of the endorsements secured by the six remaining Republican candidates.

Mitt Romney
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Per the Associated Press: "Romney's campaign says he's collected more than 1,900 endorsements, including conservative activists and current and former elected officials in all 50 states. The list includes four governors, 48 House members and 11 senators."

Gov. Nikki Haley: South Carolina governor is a first-term tea party favorite.

Gov. Chris Christie: Charismatic New Jersey leader backed Romney once Christie cemented his own decision to not run for president in 2012.

Sen. John McCain: It sounds odd given McCain’s high-profile nature as the 2008 Republican presidential nominee, but this endorsement may be more harm than help for Romney because (a) Mitt already has a big lead in New Hampshire, one of the places McCain is most popular; and (b) Team Romney has to be careful that conservatives don’t try to use the McCain endorsement to paint Romney as a moderate. At the very least, Romney’s got to be smiling about keeping this endorsement from going to Jon Huntsman Jr., who was a national campaign co-chairman for McCain in 2008.

Tim Pawlenty: The former Minnesota governor was aggressively courted by both Romney and Gov. Rick Perry last year after ending his own presidential candidacy.

Rick Santorum, 2008: Santorum's 2008 endorsement of Romney continues to pay dividends for Mitt now that the two men are competing against each other; how can Santorum’s critiques of Romney really resonate with voters after Santorum heartily endorsed the former Massachusetts governor four short years ago?

Rick Santorum
AP Photo/Charlie Riedel

Speaking of Santorum, the former Pennsylvania senator doesn’t have many endorsements to speak of — yet — and the vast majority of what he does have comes from either conservative Christians or Iowans.

Jim Bob Duggar: Star of the Reality TV series "19 Kids and Counting" brought 12 of his children with him from Arkansas to be one of Santorum’s top surrogates during the Iowa caucuses. Endorsed Mike Huckabee in 2008.

Bob Vander Plaats: President and CEO of The Family Leader, a conservative organization focused on social issues.

Chuck Hurley: President of Iowa Family Policy Center. The endorsements from Vander Plaats and Hurley were seen as endorsements from evangelical Christians, which became key in Iowa. Santorum's support there skyrocketed after these two endorsements on Dec. 20. He went from consistently polling at 3 to 6 percent in Iowa to nearly taking first place in the Iowa Caucus two weeks later.

Rupert Murdoch: The Australian media tycoon recently started posting on a Twitter account; he made waves on Jan. 2 when he tweeted, "Can’t resist this tweet, but all Iowans think about Rick Santorum. Only candidate with genuine big vision for country."

Brad Thor: Novelist and author of spy thrillers like "The Last Patriot" and "Path of the Assassin."

Ron Paul
Photo by Kevork Djansezian/Getty Images

Who’d have guessed that the 76-year-old grandfather with a fixation on the gold standard would become far and away the most popular Republican presidential candidate among celebrities? Well, it’s true.

Chuck Norris: If you find yourself wondering right now how much the endorsement of an actor with martial-arts expertise can matter, then clearly you’ve never seen the funny commercial Norris filmed with Mike Huckabee in 2008 that went viral on YouTube.

Andrew Napolitano: Former New Jersey judge, he reaches millions of viewers as an analyst for Fox News Channel.

Sen. Rand Paul: The junior senator from Kentucky is always ready to stump for dear old dad.
Andrew Sullivan: The prolific, trailblazing blogger now writes for The Daily Beast.

Kelly Clarkson: Former “American Idol” champion and Grammy-winning pop artist is the latest celebrity to endorse Paul. Heck, on Jan. 3 the Texas congressman even name-dropped Clarkson during a campaign speech.

Rick Perry
AP Photo/Dave Einsel, File

Once upon a time, the governor of Texas appeared capable of keeping pace with Romney in terms of both the quantity and quality of endorsements elicited. But all that ended after Nov. 9, when Perry’s candidacy lost its luster following his infamous "oops" moment during a televised debate.

Sheriff Joe Arpaio: As elected sheriff of Maricopa County in Arizona, the lawman has experimented with unconventional incarceration techniques like a tent city for inmates, chain gangs and pink underwear for men.

Gov. Bobby Jindal: Sitting governor of Louisiana was the first governor to endorse Perry.

Gov. Brian Sandoval: Freshman governor of Nevada.

Gov. Sam Brownback: As governor of Kansas, Brownback made national headlines in November thanks to a Twitter dust-up with a teenage girl.

David Wilkins: Former South Carolina speaker of House, he has also served as U.S. ambassador to Canada.

Newt Gingrich
AP Photo/Rainier Ehrhardt

Former House speaker’s prickly personality and the unusually high turnover of his campaign staff combine to produce a list of endorsements that’s surprisingly short for a man of Gingrich’s political stature.

Art Laffer: An economist, he helped shape Pres. Ronald Reagan's economic policy.

Don Wildmon: Chairman and founder of American Family Association and American Family Radio.

Manchester Union Leader: The largest newspaper in New Hampshire made big waves in late November by choosing to endorse Gingrich instead of Romney, the clear-cut front-runner in the Granite State.

Gov. Nathan Deal: Sitting governor of Georgia.

J.C. Watts: A four-term Congressman from Oklahoma (1995-2003), Watts was the starting quarterback for the University of Oklahoma when the Sooners notched back-to-back Orange Bowl victories in 1980-81.

Jon Huntsman Jr.
AP Photo/Stephan Savoia

Most of the former Utah governor's endorsements from come from important early voting states such as New Hampshire, South Carolina and Florida.

New Hampshire newspapers: These may not be as big as the Manchester Union Leader, but three other influential newspapers in New Hampshire have given their endorsement to Huntsman: the Keene Sentinel, Valley News and Concord Monitor.

Tom Ridge: Former Pennsylvania governor and, more recently, Secretary of Health and Human Services, Ridge is probably the most recognizable name among Huntsman’s endorsers.

Alan Wilson and Henry McMaster: They are the current and former attorneys general, respectively, of South Carolina.

Jeb Bush Jr.: This is the 28-year-old Jeb Bush — not his father, Gov. Jed Bush. Still, the Bush name always carries with it some political gravitas.

Boston Globe: After losing out on the McCain endorsement Wednesday, Huntsman wasted no time in snatching the Boston Globe's endorsement from Romney on Thursday.