Missouri Sen. Claire McCaskill says she now supports a legal right to marriage for gay couples.
The Democratic senator announced her support for gay marriage on her blog.
She said churches should never be required to conduct marriages outside their religious beliefs, but she believes that "government should not limit the right to marry based on who you love."
As recently as last year's Senate campaign, McCaskill said she had no problem with Missouri's constitutional amendment limiting marriage to between a man and a woman.
McCaskill acknowledged that her views have changed over time. She said, "Supporting marriage equality for gay and lesbian couples is simply the right thing to do for our country."
President Barack Obama announced his support for gay marriage last year.