Lots of pols know that Rudy Giuliani, should he become president, would be the first big-city mayor to sit in the Oval Office since Buffalo’s Grover Cleveland. But of more interest on K Street is that Giuliani would be the first corporate lawyer to win the presidency since Richard Nixon, who had worked at New York’s Nixon, Mudge, Rose, Guthrie & Alexander before becoming president in 1969.

Giuliani has worked at four firms, three with offices in Washington. In 2005, Giuliani joined a Texas-based firm previously known as Bracewell & Patterson, which changed its name to Bracewell & Giuliani. So much for longtime partner Harry Patterson. The firm, which largely represents oil and gas clients, has maintained offices at 2000 K Street for years.

Prior to joining Bracewell, Giuliani worked for Patterson Belknap Webb & Tyler, White & Case, and Anderson Kill & Olick.

Insiders note that Giuliani has had more firms than wives. He may be able to explain his three marriages to voters, but being grilled about his firm’s various representations—like out-of-favor Venezuelan oil company Citgo—may prove more daunting.