In February, the nomination swiftly became embroiled in the controversial DP World port deal, as it appeared that the nomination had implications of another crony appointment by Bush.
Sanborn, a graduate of the U.S. Merchant Marine Academy and a retired Naval officer, said in his letter that the day he was nominated was the proudest of his life.
"While I believe my background makes me one of the most qualified people there is for this position, the convergence of a number of factors bring me to the conclusion that I cannot effectively serve my country, you, and the U.S. maritime industry," Sanborn wrote.
Two members of the Senate Committee on Commerce, Science and Transportation, Sen. John Kerry, D-Mass., and Sen. Bill Nelson, D-Fla., put holds on Sanborn's nomination, saying "they needed to know more about his role in the process that allowed DP World to purchase the port operations in the first place."
"I hope the withdrawal of this nomination means the administration is finally waking up to the homeland security problems with our ports, not just saving face after the merciful end of the Dubai debacle," said Kerry.