Rick Santorum wants you to vote for Mitt Romney. That, of course, is according to Mitt Romney, who is trying to seal the deal Tuesday in Illinois that he will be the GOP’s nominee and anyone else at this point is merely a distraction.

To help make the point, Romney’s campaign dug up an old video of Santorum endorsing Romney for the GOP nomination in February 2008. “If you want a conservative as the nominee of this party, you must vote for Mitt Romney,” a younger, tieless Santorum says into a microphone. The TV spot that the Romney campaign produced from the video contains no other words. Except for the very end when Romney himself approves the ad.

It’s a potent message, no doubt. Just as Santorum is dinging Romney for not being a real conservative, for being too loosey-goosey and an unreliable conservative, an affirmation from Santorum that Romney is indeed a true conservative undercuts the line of attack. Quite nimble.

But it’s not exactly original. The primary system practically guarantees that such videos exist for virtually every candidate. The entire party rallies around its eventual nominee, so endorsements exist, and many of them uncomfortable. Just ask John McCain, who ran a bitter race against George W. Bush in 2000 for the GOP nomination, then fell in line and supported the would-be president. That statement and the one in which he urges support for Bush’s 2004 reelection, were uncomfortably available online when McCain tried to distance himself from Bush’s record in 2008.

The goal, naturally, is party unity. That’s what Hillary Clinton called for in 2008 when she conceded her own White House bid and asked her supporters to get behind Barack Obama. Then she went to work for him, which would be a hard reality to deny if Hillary ever wants to run again, perhaps in 2016, and contrast her vision with the Obama administration’s past.

But back to Santorum and Romney. Buried in Romney’s slam of Santorum is the accompanying truth that Romney actually attended a Santorum fundraiser in 2006. And Romney’s political action committee gave $10,000 to help Santorum win reelection to the Senate (he ended up losing).

The food fight makes for great TV and rabid tweeting among the Washington press corps. But there’s reason to believe that none of the “he once supported me!” rhetoric actually matters. A Washington Post–Pew Research Center poll earlier this year found that endorsements hardly register in voters’ minds at all. To nearly 70 percent of voters, no political recommendation would make a voter change her vote. And past endorsements are even less important, the study suggested. Voters recognize that supporting a candidate in the past isn’t the same as supporting him now. Times change, as do circumstances. And fortunately for Romney and Santorum’s past nods toward each other, they can both be grateful that soon, the news cycle will move on, as well.