(CNN) – For the subset of Republicans who viewed Mitt Romney as a Massachusetts moderate unfit for their party's presidential nomination, it could have been the dream ticket: Gingrich-Santorum for president.
Or was it Santorum-Gingrich for president?
According to a new report, the fight over whose name went atop the ballot ultimately foiled plans for Newt Gingrich and Rick Santorum to join forces against Romney last year.
"We were close," former U.S. Rep. Bob Walker told Businessweek. Walker was a supporter of Gingrich's during the GOP primaries. "Everybody thought there was an opportunity."
John Brabender, a top campaign strategist for Santorum, told the magazine the proposed ticket "would have sent shock waves through the establishment and the Romney campaign."
The planning began after the Florida primary, the report states, when Gingrich and Romney launched a record-breaking amount of negative advertising at each other to try and wrap up the GOP nomination.
Romney won the contest, propelling him into front-runner status ahead of Gingrich and Santorum, who were battling for socially conservative voters wary of Romney.
At the time, Gingrich tried to frame the Florida result as a narrowing of the field, saying it was "now clear this will be a two-person race between the conservative leader Newt Gingrich and the Massachusetts moderate."
However, Santorum characterized the Florida result as an indication of Gingrich's inability to build on his previous victory in South Carolina. The former Pennsylvania senator said conservatives were coalescing around his candidacy as the viable right-wing alternative to the more moderate Romney.
Both sides publically urged the other to drop out of the race, but behind the scenes, aides were batting around the idea of joint ticket, according to Businessweek's report. The negotiations ramped up ahead of the Michigan primary, which Gingrich and Santorum's staff regarded as a chance to stop Romney from sweeping up delegates.
But when it came time to decide who would run for president, and who would be the vice presidential candidate, the talks stalled.
Businessweek reports Gingrich "made an elaborate historical argument that when the party hasn't been able to agree on a nominee, it always settles on the senior figure."
But Santorum disagreed, arguing he had greater momentum among the conservative movement.
"I was disappointed when Speaker Gingrich ultimately decided against this idea, because it could have changed the outcome of the primary. And more importantly, it could have changed the outcome of the general election," Santorum told Businessweek.
"In the end, it was just too hard to negotiate," Gingrich said.