Steve Schmidt told a gay group, the Log Cabin Republicans, that conservatives believe the government should not interfere in private lives, CNN reported.
"I believe conservatives, more than liberals, insist that rights come with responsibilities," Schmidt said. "No other exercise of one's liberty comes with greater responsibilities than marriage. In a marriage, two people are completely responsible to and for each other."
Schmidt said he does not expect the party to drop its opposition to homosexual marriage in the near future. Both McCain and Barack Obama opposed it during the 2008 campaign.
The issue should not be decided by the courts, Schmidt said. Same-sex marriage is now legal in Iowa, Connecticut and Massachusetts because of court mandates, while the legislature legalized it in Vermont.