When Herman Cain accused Texas Gov. Rick Perry of leaking damaging information about his rival last night, there was little love lost.

Republican presidential candidate, Texas Gov. Rick Perry gestures to the audience after speaking at the Republican Presidential Forum on Manufacturing, Tuesday, Nov. 1, 2011, in Pella, Iowa. (Charlie Neibergall/AP)

Perry’s campaign has adamantly denied any involvement in a Politico story revealing sexual harassment allegations against Cain from his time at the National Restaurant Association in the 1990s. Not only did Cain suggest that Perry might be behind the leak — he stated it as a fact, despite a lack of concrete evidence.

“We now know and have been able to trace it back to the Perry campaign that stirred this up, in order to discredit me and slow us down,” Cain told supporters on a phone call Wednesday night. Cain’s chief of staff called the Perry campaign’s actions “despicable.”

While it’s the most sensational by far, it isn’t Cain’s first attack on Perry.

In September, Cain said he could not at that moment support Perry as the nominee “for a host of reasons.” Chief among them was the governor’s support for in-state tuition breaks for undocumented immigrants.

“If Governor Perry gets the nomination, I will still support him, but it won’t be 100 percent,” he later elaborated. He’s also called Perry a “career politician” who doesn’t deserve credit for Texas’ “business-friendly” culture.

Cain’s demand of purity from Perry is somewhat odd, given Cain’s own vacillations on numerous issues. Moreover, Cain has said that he would stand behind former Massachusetts governor Mitt Romney (who he endorsed in 2008) despite that candidate’s many past deviations from conservative orthodoxy.

The only African-American candidate in the GOP field, Cain was also one of the only candidates to criticize Perry for a racial slur found on a rock at the governor’s hunting camp. (Cain later backed away from his words in the face of conservative anger.)

In debates, Cain and Romney have been relatively friendly while both clash with Perry.

But the animosity is largely one-sided. While Perry has challenged Cain’s tax plans, he’s prefaced his complaints with praise while saving his anger for Romney. In one debate, Perry led into a criticism with “Herman, I love you brother.” (That phrasing itself was attacked for being potentially insulting, though Perry denied it was meant that way.)

Asked about his own sinking poll numbers in mid-October, Perry said, “Herman Cain is one of the most interesting people sitting on that stage.”

While the Perry campaign has had some harsh words for Cain since the accusation, they are now minimizing this spat.

“Gov. Perry knows that the primary is a competitive, rough-and-tumble process,” said Perry spokesman Ray Sullivan. “But we’re confident that when he is the nominee, the other candidates in the party will rally around the conservative standard-bearer to defeat the president.”

Politically, Cain and Perry occupy similar territory. Both have positioned themselves as straight-talking political outsiders; both come from the South. Cain’s rise in polls tracked directly with Perry’s collapse.

“There is a zero-sum relationship between how well Cain and Perry do,” Quinnipiac pollster Peter Brown said last month. Of course, the candidate who will gain most if Cain collapses from this scandal isn’t Perry — it’s Romney.

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