President Barack Obama on Monday nominated Chuck Hagel, a former Republican senator from Nebraska and Vietnam veteran, to succeed Leon Panetta as secretary of defense.

“Chuck Hagel's leadership of our military would be historic,” Obama said in announcing his decision. “He'd be the first person of enlisted rank to serve as secretary of defense, one of the few secretaries who have been wounded in war, and the first Vietnam veteran to lead the department.”

Citing Hagel's poor record on gay rights in the Senate and comments he made in 1998 toward James Hormel, the openly gay former U.S. ambassador to Luxembourg, gay rights groups have largely opposed Hagel's nomination.

Reaction to Monday's official announcement was decisively mixed.

Former Massachusetts Rep. Barney Frank, who questioned Hagel's recent apology to Hormel, said he was prepared to back Hagel.

“As much as I regret what Hagel said, and resent what he said, the question now is going to be Afghanistan and scaling back the military,” he told the Boston Globe. “In terms of the policy stuff, if he would be rejected [by the Senate], it would be a setback for those things.”

Wisconsin Democrat Tammy Baldwin, the Senate's only openly gay member, questioned the sincerity of Hagel's apology.

“I do want to speak with him, particularly about his comments 14 years ago, to see if his apology is sincere and sufficient,” Baldwin said on MSNBC's Andrea Mitchell Reports. “I want to hear how he's evolved on this issue in the last 14 years.”

Gay GOP group Log Cabin Republicans did not retreat from its opposition to Hagel, The group has been running expensive full-page ads in The New York Times and The Washington Post opposing Hagel as the nominee.

Gregory Angelo, the group's interim executive director, called Hagel's apology “weak” during an appearance on MSNBC. He also cited Hagel's support for the Defense of Marriage Act (DOMA) and “Don't Ask, Don't Tell” while in the Senate.

Allyson Robinson, executive director of OutServe-SLDN, which represents LGBT troops, also cited concerns over DOMA but left open whether the group would support Hagel.

“Our message to the next Secretary of Defense would be the same, no matter who was nominated and confirmed,” she said in an email to supporters. “A commitment to support LGBT service members and their families must be a commitment to action. It's past time to extend all benefits available to married same-sex military couples and families while the so-called Defense of Marriage Act (DOMA) is still on the books. It's past time to put in place military equal opportunity and nondiscrimination protections so that all qualified Americans who wish to serve this nation in uniform may do so without fear of harassment or discrimination. We look forward in the weeks ahead to discussing these and other issues important to LGBT service members and their families with Senator Hagel and his designees, and to working with him should he be confirmed to create equitable conditions for all those who serve our nation so bravely in uniform.”