When Gov. Chris Christie pushed to expand financial incentives to keep businesses in New Jersey, one of the first companies to benefit was a client of David Samson, a lawyer with a long and close relationship to the governor.

When Mr. Christie announced government-backed financing for college and school construction projects, Mr. Samson’s firm got a piece of that business.

And after Mr. Christie named Mr. Samson chairman of the Port Authority of New York and New Jersey, they both benefited when Mr. Samson and the board he led approved billions of dollars in bridge construction contracts. Labor unions grateful for the hard-hat jobs threw their endorsements to Mr. Christie, and clients of Mr. Samson’s firm wound up with the work.

The lane-closing scandal that has enveloped Mr. Christie’s administration and the Port Authority for months has focused intense scrutiny on Mr. Samson and the 120-lawyer firm that he helped found in 1972. A number of potential conflicts have been reported by other news media, and the agency’s executive director, Patrick J. Foye, last week said that Mr. Samson lacked the moral authority to remain chairman.