Updated 04/02/13 – 2:38 p.m.

CHICAGO (CBS) — Republican U.S. Sen. Mark Kirk has announced his support for gay marriage, saying that legally discriminating against same-sex couples “is an anathema to me.”

In a statement on his Senate website, Kirk said: “When I climbed the Capitol steps in January, I promised myself that I would return to the Senate with an open mind and greater respect for others.

“Same-sex couples should have the right to civil marriage. Our time on this earth is limited, I know that better than most. Life comes down to who you love and who loves you back — government has no place in the middle.”

Kirk, Illinois’ ranking Republican lawmaker in D.C., returned to the Senate in early January, nearly a year after suffering an ischemic stroke. He becomes the second Republican in the U.S. Senate to publicly support same-sex marriage, joining Ohio’s Rob Portman.

Kirk told the Illinois Radio Network on Tuesday that the issue of same-sex marriage is personal to him.

“My best friend in high school was one of the first people to be married legally in the United States,” he said.

He said the country is ready to accept marriages between same-sex couples.

“The gay community is larger than ever before and it’s not in the 1950’s closet so most of us have gay acquaintances at work or at church and we know them and the thought of legally discriminating against our own friends and co-workers is an anathema to me,” Kirk said.

The senator said viewing director Stephen Spielberg’s movie “Lincoln,” about President Abraham Lincoln’s work to pass the 13th Amendment banning slavery helped shape his opinion.

“I must say I’ve been pretty influenced by the latest Spielberg movie about Abraham Lincoln,” Kirk said. “As a Republican leader, my job is to make sure that each generation is more free, and has more dignity as an individual, which is a unique gift of the United States to the world, and the thought of treating a whole bunch of people, just because of who they love, differently, is in my view against that Lincoln tradition.”

Kirk previously voted to end the military’s “Don’t Ask, Don’t Tell” policy on homosexuals serving openly in the military, and also voted against a constitutional amendment to ban gay marriage.

Equality Illinois CEO Bernard Cherkasov said he’s pleased not only with Kirk’s support of same-sex marriage, but his explanation for it.

“You know, when he returned back to the U.S. Senate after his stroke, he talked about being more open-minded and putting himself into the shoes of others,” he said. “And he said that when he really thought about the meaning of life, it came down that life is really all about people you love, and who love you back.”

Kirk’s support for same-sex marriage comes as the Illinois House is weighing legislation to legalize same-sex marriage. The House Executive Committee endorsed the measure by a 6-5 vote in February, sending the bill to the full House, but sponsors have yet to call for a vote by the entire chamber.

The Illinois Senate approved the measure on Valentine’s Day, by a 34-21 vote, with only one Republican voting yes.

University of Illinois at Chicago political science professor Dick Simpson said he thinks Kirk’s support for gay marriage is a sign that public attitude toward same-sex marriage is changing, and ultimately will be legalized in Illinois.

“I think there’s been continual announcement of more support. I think gay marriage is clearly going to win in the end,” he said. “I think it means that gay marriage is going to pass. I think it may pass in Illinois this time around.”

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