Former Republican Congressman Mark Neumann announced Monday he was running for the U.S. Senate seat held by retiring Wisconsin Democrat Herb Kohl, according to the The Associated Press, making him the first to officially announce his candidacy in the 2012 race.

Neumann lost a Senate bid to Russ Feingold in 1998 and lost a Republican gubernatorial primary to Scott Walker last year. noted that he has made several homophobic remarks, including saying that if he were God, "homosexuality wouldn’t be permitted," and saying he wouldn’t hire an openly gay staffer.

If he wins the Republican nomination, Neumann is likely to face Wisconsin Congresswoman Tammy Baldwin, the first openly gay candidate to win election to the U.S. Congress.

“I believe our opponent is Tammy Baldwin and I believe it is essential that we bring Tammy Baldwin’s record to the forefront,” Neumann said.

Baldwin has not officially entered the race, but has previously said she is likely to run for the Senate seat.

Two other Democrats, U.S. Congressman Ron Kind and former U.S. Congressman Steve Kagen, are also considering running for the seat, but a recent survey by Public Policy Polling suggests Baldwin is the early favorite among Democrats.