(Corrects 4th paragraph to read 58 seats instead of 59 seats)
(Adds background)
WASHINGTON, Feb 1 (Reuters) - Democrats would not increase their margin of control in the Senate if New Hampshire Republican Sen. Judd Gregg leaves to serve as commerce secretary, Senate Minority Leader Mitch McConnell said on Sunday.
"Sen. Gregg has told me that if he were to take this appointment, it would not alter the makeup of the Senate in terms of the majority and the minority," McConnell said on CBS's "Face the Nation."
Gregg has emerged as Democratic President Barack Obama's top candidate for commerce secretary and a decision could come as early as Monday.
Democrats currently control 58 seats in the Senate, and are leading in one other undecided race, just short of the 60 needed to clear Republican procedural hurdles.
McConnell's comments suggested that a deal had been struck to ensure that New Hampshire's Democratic governor, John Lynch, would not name a Democrat as Gregg's replacement.
(Reporting by Andy Sullivan)