President Obama, in pushing for a repeal of the law ban homosexuals from serving openly in the military, is forcing lawmakers from both parties to gingerly explore this white-hot and divisive issue with months to go until midterm elections.

House Republican Conference Chairman Mike Pence, R-Ind., likened an alteration to the Pentagon's so-called "don't ask, don't tell" policy to "some social experiment."

"The burden of proof is on this administration," said Pence. "That a repeal of 'don't ask, don't tell' will make us safer."

House Majority Leader Steny Hoyer, D-Md., said that rank-and-file lawmakers want to first hear what the military proposes doing with the 17-year-old policy. In his State of the Union message last week, Obama asked the military brass to scrap the policy so gay persons could serve openly in the armed forces.

Hoyer noted that Joint Chiefs of Staff Chairman Adm. Mike Mullen had served in the military since the late 1960s and that many Members of Congress want the chairman to weigh in before implementing a policy change.

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"Obviously there have been gays in the military from then to now," Hoyer said.

Defense Secretary Robert Gates and Mullen addressed some of those questions Tuesday at a Senate hearing, saying it is time to allow gay troops to serve openly for the first time in history. Mullen said service members should not be forced to "lie about who they are."

However, both Gates and Mullen asked for a year to study the impact before Congress would lift the controversial policy.

Reversing the Pentagon's 17-year-old policy toward gays "comes down to integrity," for the military as an institution as well as the service members themselves, Mullen told the Senate hearing. Unpersuaded, several Republican senators said they would oppose any congressional effort to repeal the policy.

It's likely that President Obama could ask for legislation to change the "don't ask, don't tell" policy. Pence described that as a "relief."

"We're not going to have an executive order foisted on us," Pence said.

While many gay groups applaud the president's effort to eliminate "don't ask, don't tell," Republicans walk a fine line of further alienating a voting bloc that's traditionally sided with Democrats. But Pence argued that lifting the existing rule would just be bad policy.

"This is not about a moral or cultural debate," Pence said.

The Associated Press contributed to this report.