When Mitt Romney and Rick Perry aren’t berating each other on the debate stage, with body language more befitting a bar fight, their campaigns are busy lobbing highly charged attacks back and forth: “Ponzi scheme,” “Romneycare,” “no heart” (on immigration),” “flip-flop.” And the newest verbal grenade: “tax returns.”

Earlier this week Perry spokesman Mark Miner told Politico, which had first reported the story, that “Governor Perry has always released his tax returns and Mitt Romney and the other candidates should do the same.” If history is any indication, watch for Perry to push that theme hard, and for Romney to remain firm in his decision to keep his returns private. “We’ll take a look at the question of releasing tax returns during the next tax filing season,” says Romney spokeswoman Andrea Saul about the Perry campaign’s request. By then, of course, the primary campaign could be effectively over.

Perry communications director Ray Sullivan responds: “Governor Perry made a decision a long time ago in the interest of disclosure and transparency [that] he would make his personal tax returns available. That is a wise thing to do and helps gain the trust of the voters. It would be for other candidates to do the same.” Will Perry himself start calling on Romney and others to release their tax returns? “That remains to be seen.”

For both men, this is not the first time a campaign has included a “tax returns” chapter. Although Romney has campaigned on the issue, he has never released a tax return, while Perry has released his returns dating back to 1987, according to the Texas Tribune.

For Perry, the issue first arose in 1998. During a heated debate, John Sharp, Perry’s Democratic opponent in the lieutenant governor’s race, called on Perry to release his tax returns. A week later, Perry made his returns from 1991 to 1996 (the most recent years he had filed for) publicly available, according to the Dallas Morning News.

In Perry’s 2002 gubernatorial race against Democrat Tony Sanchez, tax returns again played a role, and this time Perry’s camp was the aggressor. “The people of Texas deserve to know the financial history of the men and women who seek to represent them,” argued Deirdre Delisi, Perry’s campaign manager at the time. Sanchez released partial information about his finances for the previous decade, but Perry kept demanding that he release his complete returns.

In the 2010 gubernatorial race, Perry refused to debate with Democratic opponent Bill White until White released his tax returns. When White released the returns from 2009, Perry continued to push: He wanted returns from the years when White was deputy secretary of energy in the Clinton administration. “He needs to come clean with the people of this state,” Perry said of White. “There’s obviously something in those tax returns, or he would have released them by now.”

The Perry campaign has no plans to tie debate appearances to tax-return releases in this race, but for Perry, a man of significantly more modest means than Romney, pushing the issue could underscore Romney’s wealth in a time of economic hardship for many. It’s unclear how well that would work in a Republican primary — in which voters are more interested in becoming the 1 percent than attacking it — but for Perry, it would be a return to a familiar strategy.

Like Perry, Romney has been both aggressor and target on the tax-return front. In 1994 Romney called on Ted Kennedy, whom he was seeking to unseat as senator from Massachusetts, to release his tax returns if he truly had “nothing to hide.” Romney promised he’d release his own three most recent years of tax returns if Kennedy did so, saying, “It’s time the biggest-taxing senator in Washington shows the people of Massachusetts how much he pays in taxes,” according to the Boston Globe. Kennedy never released his returns. Neither did Romney.

In Romney’s 2002 gubernatorial race, Democratic candidate Shannon O’Brien released her tax returns and pressured Romney to do the same, to no avail. O’Brien called Romney’s refusal hypocritical in light of his 1994 pressure on Kennedy, saying in a debate that “once again, this is an issue of [Romney] saying one thing and doing another.”

In the 2008 primary cycle, Romney benefited from the fact that almost no one in either party was any more forthcoming about their finances. In May 2007 ABC News reported that “of the six front-runners, all of them millionaires, only Senator Barack Obama has released his tax returns.” (The others were Romney, Rudy Giuliani, John McCain, Hillary Clinton, and John Edwards; McCain later released his returns.) Mike Huckabee was not considered a front-runner, but he didn’t make disclosure an issue either; in the 1990s, Politico reported, he had been forced to file amended tax returns for a couple of years after releasing 15 years of returns, and he apparently had little appetite for risking a similar situation.

Today the Romney campaign is fighting back by pointing out that unlike Romney, Perry has not yet filed the financial disclosures required by law for presidential candidates (last week he asked for a second 45-day extension). They also bring up Perry’s travel records. “The Perry campaign is in no position to lecture anyone on disclosure,” says Saul. “They have been stonewalling on releasing the most basic records involving taxpayer-funded spending in Texas as it relates to Governor Perry’s travel records. Governor Perry should immediately release these public documents.”

“We are in and will remain in full compliance with the federal disclosure requirements, and in fact, the governor has gone beyond state and federal requirements by [releasing] years of personal tax returns,” Sullivan retorts. (By filing for an extension, the campaign has complied with the requirements.) Regarding travel, he says, “Virtually all of the governor’s travel is paid for by campaign or private [funds]. We rarely use taxpayer-financed travel, and that has been a policy in place for many years.”

Wresting away the nomination from Romney, whom many pundits see as a shoo-in at this point, will be no easy task. If tax returns prove to be a chink in Romney’s armor, watch for the Perry campaign to try to capitalize on it at every opportunity.

“He just hammered it, hammered it,” says Bill Miller, an Austin-based lobbyist. “Every time Rick Perry talked, he talked about it. It turned into something that was a negative from day one in the White race.

“It was a great issue for Governor Perry,” Miller adds, “and he used it very, very effectively.”

— Katrina Trinko is an NRO reporter.