WASHINGTON -- Sen. Dianne Feinstein (D-Calif.) defended President Barack Obama on Sunday from Republican charges that he has "flip-flopped" by speaking out in favor of marriage equality rights for same-sex couples.

When asked whether Obama had made a political calculation in endorsing gay marriage, Feinstein rejected the idea.

"I don't think it is a flip flop and there is no political calculus in this, because it is not smart from a political point of view. It doesn't make sense," Feinstein said.

"From a personal point of view, I can tell you what happened because it happened to me," she continued. "You get to know more and more gay couples and you see the happiness. You see the economic security that marriage brings. And even more fundamentally, you can see children who otherwise would not have an adopted home being able to have that home. And so same-sex couples raise children, they do a fine job. And I think when you see this -- and it has happened in California -- more and more people say, 'What is wrong with people being happy?'"

Later on Sunday, speaking on ABC's "This Week," Rep. Barney Frank (D-Mass.), the first openly gay member of Congress, pushed back against claims that Obama's position on the issue would harm him politically. Obama has already repealed the military's "don't ask, don't tell" policy and has stopped enforcing the Defense of Marriage Act, while presumptive GOP presidential nominee Mitt Romney has opposed both marriage and civil unions for gay couples.

"I don't think this changes anyone's vote," Frank said, referring to Obama's support for same-sex marriage.