SANTO DOMINGO, Dominican Republic — It turns out that the lucrative port security contract pushed by Senator Robert Menendez would enrich more than just a major benefactor.

The contract could also benefit one of the senator’s former top aides, people connected to the deal said.

Mr. Menendez, Democrat of New Jersey, has pushed United States government officials to help enforce a contract that a company owned in part by one of his major donors, Dr. Salomon E. Melgen, has with the Dominican government, which has refused to honor it.

A top executive at Dr. Melgen’s security company will be Pedro Pablo Permuy, a former national security adviser and senior legislative aide to Mr. Menendez, according to a cousin of Dr. Melgen. Mr. Permuy’s ties to the senator go back at least 20 years.