In recent days, there’s been a new word sneaking into the mouths of Mitt Romney’s surrogates: Chicago.

Hoping to counter Obama’s personal, brutal attacks on Romney’s Bain Capital record and refusal to release tax returns, Romney’s campaign has seized on a line of attack that Sen. John McCain (R-Ariz.) used intermittently throughout the 2008 campaign — that Obama is a sleazy Chicago pol.

BuzzFeed reports that surrogates for Romney plan to bring up former Illinois governor Rod Blagojevich as well. Obama “really hasn’t been vetted; McCain didn’t do it,” an adviser said.

Republican lobbyist Ed Rogers said Obama’s Chicago history was “fair game.” But “Romney will only win if voters think Obama has failed on the economy and Romney would be better,” he said. “He shouldn’t be tempted or distracted by hand-wringers who want him to refight old fights.”

McCain did attack Obama on his Chicago ties. In August 2008, he focused on Tony Rezko, “a convicted felon facing jail.” A September ad said Obama was “born of the corrupt Chicago political machine.” In the final days of the campaign, two weeks before the election, McCain released mailers and robocalls on Rezko.

The Republican National Committee chimed in with an ad tying together Rezko, Bill Ayers and Bill Daley: “The Chicago Way. Shady politics. That’s Barack Obama’s training.”

Polls suggest Rezko was not a very potent weapon back in 2008. An October New York Times-CBS poll found that of the 44 percent bothered by “anything” related to Obama’s background, only one person mentioned Rezko.

But McCain’s attacks were sporadic — nothing like the sustained campaign Obama has waged against Romney’s business history and tax returns. And Romney’s camp argues that the Chicago attack plays into a broader case that Obama paid off allies while in office.

“I think people understand Chicago-style politics,” Romney spokeswoman Gail Gitcho told Lynn Sweet. “Paying off your friends, and that’s what President Obama has done, and that’s what we are highlighting.”

Of Obama’s negative ads, Romney said on Fox News Monday, “It may work in Chicago, but it’s not going to work across America.”

On a conference call that same day, senior adviser Ed Gillespie accused Obama of paying off political donors, calling it “essentially Chicago-style politics and Chicago-style economics.”

Former New Hampshire governor John Sununu (as he often does) went a step further, bolstered by Obama deputy campaign manager Stephanie Cutter’s suggestion that Romney may have lied on SEC filings, “which is a felony.”

If we’re going to talk about felonies, Sununu argued on Fox News, “this is a president who wallowed in Chicago, in the murky soup of politics-slash-felons. This is a president who cut a very snarky real estate deal with Tony Rezko, who is now in prison.”

A few days earlier, the conservative media conglomerate used the felon comment as a hook for a list of the “top ten felons, fugitives, and shady characters in Obama’s life.”

So far, these allegations have yet to find their way into a paid media campaign. That would be a sign that Romney thinks this line of attack is a winning strategy and not just a chance at moving attention off Bain Capital for a few days.