Washington, D.C. (AP) - Mitt Romney apologized Thursday for "stupid" high school pranks that may have gone too far and moved quickly to stamp out any notion that he bullied schoolmates because they were gay. His swift response reflected the Republican presidential candidate's recognition that his record on gay rights is under heightened scrutiny following President Barack Obama's embrace of gay marriage.

One day after gay rights moved to the center of the presidential race with Obama's announcement on same-sex marriage, a Washington Post report about Romney's high school escapades nearly 50 years ago added a personal dimension to Democrats' claim that he's out of step on the sensitive topic.

The newspaper reported that in one case, Romney and several schoolmates held down classmate John Lauber and cut off his bleached blond hair after seeking him out in his dorm room at their boarding school in the wealthy Detroit suburb of Bloomfield Hills, Mich. The Post said Lauber was "perpetually teased for his nonconformity and presumed homosexuality" and that he screamed for help as Romney held him down. The paper recounted another incident in which Romney shouted "atta girl" to a different student at the all-boys' school who, years later, came out as gay.

"I participated in a lot of hijinks and pranks during high school and some may have gone too far. And for that I apologize," Romney told Fox News' Brian Kilmeade during a hastily arranged radio interview. Romney said he didn't remember the Lauber incident from long ago, but didn't dispute that it happened. He stressed that he didn't know either student was gay.

The Republican presidential candidate had begun the day by treading softly on Obama's historic embrace of same-sex marriage, which seems likely to fire up liberal and conservative activists alike. He quietly restated his opposition to legalizing such marriages, but his campaign turned its full attention to energy, the economy and other issues.

Then the boarding school story was posted online and Romney moved quickly to counter any suggestion he had targeted students because they were gay.

"That was the furthest thing from our minds back in the 1960s, so that was not the case," he said, adding that the students involved "didn't come out of the closet until years later."

According to the Post account, Romney was upset about how Lauber wore his bleach-blond hair hanging into his eyes.

"He can't look like that. That's wrong. Just look at him!" Romney told Matthew Friedemann, a close Romney friend and one of five classmates who recalled the incident for The Post. A few days later, Romney led a group of boys out of his dorm room at Cranbrook School and into Lauber's, where the group tackled him and held him down. Romney cut his hair with scissors as a teary-eyed Lauber screamed for help.

"If there was anything I said that was offensive to someone, I certainly am sorry about that," he said, adding that "there was no harm intended." Romney's campaign has previously highlighted the candidate's reputation as a high school prankster in an attempt to humanize him.

In a second interview Thursday, Romney laid out what he said was his long-held position on gay rights: While opposed to gay marriage, he said states should be allowed to grant various domestic partnership rights to same-sex couples, including the right to adopt children.

"States could have their own decisions with regards to the domestic partnership rights," Romney told Fox News. "But my preference would be to have a national standard for marriage, and that marriage would be defined as being between a man and a woman."

He said he would go as far as supporting gay couples who want to adopt children, saying: "If two people of the same gender want to live together, want to have a loving relationship and even want to adopt a child - in my state, individuals of the same sex are able to adopt children - in my view, that's something which people have the right to do."

The GOP candidate defended some gay rights when he ran for governor of Massachusetts but was a leading voice against gay marriage when courts made it legal in the state.

"We would have never gotten as far as we did without Gov. Romney's very strong support," said Kris Mineau, the president of the Massachusetts Family Institute, the group that spearheaded the fight for the state constitutional amendment.

Still, when Romney ran for Senate in 1994, he argued that he would be a better advocate for gay rights' issues than Democratic Sen. Ted Kennedy because he would make gay issues mainstream. "I think the gay community needs more support from the Republican Party and I would be a voice in the Republican Party to foster anti-discrimination efforts," he said in a 1994 interview.

Obama on Wednesday became the first president in history to support gay marriage, and Romney was careful to use empathic language as he responded to that decision.

"This is a very tender and sensitive topic as are many social issues, but I have the same views I've had since running for office," Romney said, a rhetorical contrast with some of his sharper responses on issues like immigration.

Romney's advisers signaled they planned to campaign on the issue in November's election, but acknowledged they would have to tread carefully. "I think it's important to be respectful in how we talk about our differences, but the fact is that's a significant difference in November," Ed Gillespie, a senior Romney adviser, said Thursday on MSNBC.