Are you familiar with the endorsement game? The way it works is, a political candidate announces that so-and-so is gung ho for the candidate - and that therefore, supposedly, the voters should be just as gung ho, now that the candidate has been publicly vetted by so-and-so.

The game has already begun among the warring Democrats in Pennsylvania, where Democratic congressmen Joe Sestak is trying to wrest the '10 Senate nomination away from arriviste Democrat Arlen Specter. We now have official word from the Sestak camp that the upstart challenger has been endorsed by prominent House liberal Barney Frank, and by Lieutenant Dan Choi, an Iraq war veteran who was subsequently discharged for being gay.

It's easy to divine Sestak's intentions here. Six months away from primary day, most Pennsylvania Democratic voters still know relatively little about the guy; by parading these two endorsements, Sestak is trying to tell the liberal base that he has the requisite credentials. Since he remains largely undefined at this point, he wants Frank and Choi to help define him.

But here's the thing about most political endorsements: In the end, they tend not to mean squat. Just do the "hey, honey" test, and you'll see:

A spouse is reading the news over a cup of coffee. Then he says, "Hey honey, did you see where Barney Frank and Dan Choi endorsed Joe Sestak in the Senate race? Wow, I'm going to vote for Sestak!"

Care to guess how often this leap of logic has been articulated this week among Democratic voters in the Keystone State?

I say this not to malign Sestak's candidacy; quite the contrary, I expect him to run strong next spring. I'm merely ragging on the endorsement game, which always hinges on the assumption (disproved again and again) that voters care a whit about who vets who. (Nor do they care much about newspaper editorial endorsements, either.)

The candidates know this is an empty game, even as they to play it. Long before John Edwards became a joke, he was a serious endorsement gamesman. In the summer of '07, he released a list of "prominent Latinos" and "African-American leaders," all of whom had signed on as endorsers. Flash forward to May of '08; at this point, Edwards was an ex-candidate, and thus apparently willing to be candid. In an interview with NPR, he said that endorsements are "blown way, way out of proportion...I don't think they make a huge difference...I think the vast majority of voters make their own judgment about the candidates and decide who to vote for on that basis."

Another example: Rob Portman, currently the top Republican senatorial candidate in Ohio, recently trotted out the names of 150 big shots who have endorsed his bid; the list includes House Republican leader John Boehner and the top two guys in the Ohio state senate. Then, not long ago, he added this observation of his own: "I think endorsements are overrated, even the ones I've made."

Speaking of overrated, I'll never forget the time I attended a Howard Dean rally on the eve of the 2004 Iowa Democratic caucuses. Dean had just been endorsed by Al Gore and a host of other prominent Democrats. On this particular night, Dean stood on the stage of this drafty assembly hall, and unveiled his supposedly secret weapon: Iowa Democratic senator Tom Harkin. The veteran liberal lawmaker had held back his endorsement until the last phase of the campaign, so as to maximize his impact on the Democratic caucus-goers. And what happened? Harkin had zip impact. Gore had zip impact. Dean wound up finishing third with a mere 18 percent, thus triggering his swift plummet.

And speaking of overrated, Barack Obama's twin '08 endorsements from Edward and Caroline Kennedy didn't even help him in Kennedy country; Hillary Clinton waxed him by 17 points in the Massachusetts primary. And out in California, Obama garnered high-profile endorsements from the top Latino labor leaders, all of whom had grassroots organizing prowess - but Obama still lost the Latino voters by a margin of nearly 2-1.

Granted, presidential candidates are fairly well known, which means that voters have plenty of information already, thus diminishing any endorser's impact. The theory is that a big endorser might have more clout in a race where a candidate is little known (such as Sestak). But this is no cinch bet, either. Last July, Georgia Democrats staged their own Democratic senatorial primary. An exciting new face, businessman Rand Knight, racked up endorsements from all the top ground-game groups, including the Georgia AFL-CIO, the Georgia Association of Teachers, 25 other local unions, plus the National Education Association. When the smoke cleared on primary night, Knight got five percent of the vote.

Last night, meanwhile, the Massachusetts Democrats staged a primary, to choose a candidate for the seat long held by Ted Kennedy. Caroline Kennedy made an endorsement. The candidate whom she endorsed wound up finishing third.

But the game goes on anyway. In the Texas Republican gubernatorial primary, Kay Bailey Hutchinson just did a stump appearance with a prominent endorser, Dick Cheney. Her opponent, incumbent Gov. Rick Perry, has his own big endorser, Sarah Palin. Will Texans really vote on that basis?

As for Sestak, this week's Barney Frank endorsement has potential symbolic value. On the other hand, Frank is a volatile guy with a high-profile committee chairmanship; if he says or does anything controversial, Sestak's opponents may well demand that Sestak take a stand on whatever Frank said or did. That's also part of the endorsement game.

But let's give the last word to Dick Gephardt. Remember him? Former House Democratic leader who tried and failed several times to run for president? When he endorsed Hillary Clinton during the summer of '07, he had this to say, with respect to the alleged value of endorsements: "I'm a has-been politician, so I don't know that I can do anything more than bring my own vote, but maybe I can get my family to vote the right way."

It's a shame that the has-beens are usually the only ones who feel free enough to give away the game.