Weekly Standard editor Bill Kristol has been one of the more prominent thorns in Mitt Romney’s side throughout the 2012 presidential contest, but their differences go all the way back to the early 1990s.

Kristol has boosted Romney’s rivals who are in the race for president and practically begged some of the GOP’s hottest stars to enter it.

On a panel on Fox News while the Iowa caucus votes were being counted, Kristol roasted Romney all night long, saying the photo finish was a big victory for former Sen. Rick Santorum, who ultimately lost to Romney by 8 votes.

“The Romney inevitability story, which they put a lot of weight on in making the case for themselves, has taken a big hit,” Kristol said.

As it turns out, the two share a bit of ancient history from 1994, when Romney was running for Senate in Massachusetts against the late Sen. Edward Kennedy (D).

Kristol had just boosted another GOP candidate in California, Michael Huffington, by preparing him for a televised debate with Sen. Dianne Feinstein (D).

The late Greg Stevens, of “Dukakis tank ad” fame who was producing television spots for Romney, pitched the campaign on bringing in Kristol to prepare Romney for his debates with Kennedy.

Charley Manning, the surprisingly liberal Republican consultant who was calling most of the shots on the campaign, immediately vetoed the idea. “The Boston Globe will have a field day with that,” Manning told fellow campaign aides on a conference call, according to a Republican operative who worked on the campaign.

Manning, who did not return a call for comment, was “terrified” that bringing in Kristol would make Romney look “too right wing,” the source added.

It’s unclear whether Romney even knew about the exchange, and it wasn’t more than a blip on Kristol’s radar screen, either.

“I have no memory of it,” Kristol said in an interview. “What did he lose by, 17 points? He probably would have lost by 18 or 19 if I had gone in to help him. Or, I could have helped him win, and then he would have become a career politician and that would have been terrible for him.”

Years later, when Romney was governor, he invited Kristol to dinner. “We had a very nice dinner in Boston when I was teaching at Harvard,” Kristol said, adding that the two have met several times since then to discuss policy issues. “I both like him and am impressed with him.”

Kristol explained that the fierceness of his opposition to Romney stems from the fight he is waging with fellow members of the GOP establishment.

“There’s this kind of crazy, not crazy, but kind of bewildering assumption on the part of the Republican establishment that it’s just obvious that Mitt Romney’s the most qualified guy,” he said. “So if you’re not for him it’s because you’re either kind of an ideological purist or some kind of, you know, troublemaker or tea party lunatic or something.

“It’s like, really? Is it so obvious that he was that much better a governor of Massachusetts than Rick Santorum was a Senator from Pennsylvania? Or even with all his problems, Newt Gingrich was after all Speaker of the House and did some pretty important things there for four years,” Kristol added. “It wasn’t like he was considered the best governor in America or something. … The one most distinctive thing he did was obviously Romneycare.”

He allowed that polling shows Romney doing better in a head-to-head matchup with President Barack Obama but argued Santorum might appeal more to a different type of independent voter.

Romney “does appeal to a certain kind of independent who is important to appeal to; let’s call it a socially moderate, fiscal conservative business suburban type, who are incidentally the kinds of independents that journalists tend to know personally and live next door to,” Kristol said.

“It’s not clear he appeals as well as Santorum would to the other kind of swing voter: the lower-middle-class churchgoing Reagan Democrat from exurban Toledo,” he added. “I’d kind of like to see these guys actually go campaign. Let’s see what happens when some states actually vote.”

A spokeswoman for Romney did not respond to a request for comment.