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If Mitt Romney picks Rob Portman as a running mate, Democrats will immediately pounce, portraying him not just as Bush crony but also a former lobbyist for overthrown Haitian dictator Jean Claude "Baby Doc" Duvalier.

That's quite an explosive allegation. Baby Doc was a notorious and blood-thirsty dictator. But there's one problem with the allegation: It's not true.

First, some background.

As a young lawyer in the mid-1980s, Portman had a two-year stint working for the Washington-based lobbying firm Patton Boggs. In a lobbying registration form filed at the time on June 8, 1985, Portman lists five foreign entities who were clients of Patton Boggs and writes that, as an attorney for the firm, he "may be engaged in performance of legal and related services" for them. The clients listed include "Republic of Haiti", "The Government of the Sultanate of Oman" and "Duty Free Shoppers, Ltd."

This is a standard disclosure required of lobbyists who work at firms with foreign clients. The registration makes it possible to do work for the clients, but does not mean any work was actually performed.

Portman's Senate office has provided what appears to be solid evidence that he, in fact, did no work for Haiti or Oman or, for that matter, any foreign government.

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In a signed affidavit provided by Portman's staff and dated April 12, 2005, the managing partner of Patton Boggs, Stuart Pape, says flatly that Portman did no work for any foreign government during his relatively short stint with the firm. Pape, by the way, is a prominent Democratic lobbyist.

"I have reviewed the time records maintained by the Firm for the entire period in which Mr. Portman was an associate attorney with the Firm," Pape says in the affidavit.

"Those records confirm," Pape says, that "at no time did Mr. Portman do any work for any foreign government or entity of a foreign government."

Portman did, however, do work for Duty Free Shoppers, LTD, which, at the time, was a Hong Kong-based chain of Duty Free stores at airports around the world. Not quite the same as doing work for a murderous Haitian dictator.