(CNN)-- President Barack Obama's announcement that he now supports same-sex marriage came sooner than planned as a result of comments made by Vice President Joe Biden, he said in an interview broadcast Thursday.
"I had already made a decision that we were going to probably take this position before the election and before the convention," Obama told ABC's "Good Morning America," referring to the Democratic National Convention in September.
Biden "probably got out a little bit over his skis, but out of generosity of spirit," the president said.
He added that he would have "preferred to have done this in my own way, on my own terms," but "all's well that ends well."
Biden told NBC's "Meet the Press" over the weekend that he is "absolutely comfortable" with same-sex marriage.
Multiple top Democrats told CNN the president's senior aides are annoyed with Biden for forcing the conversation on same-sex marriage now. One source said Biden has, in the past, counseled the president against coming out for same-sex marriage -- making this move that much more frustrating.
The sources said they don't believe it will create a lasting rift between the two. Biden is known to go off script, something the president was aware of when he selected his vice president.
But once Biden's comments drew attention to the issue, Obama made plans to announce his support next week on a previously scheduled appearance on the ABC talk show "The View," a senior administration official said Thursday. The president and his advisers knew Obama would be asked about the issue in the wake of Biden's NBC interview, said the official, who didn't want to speak publicly about internal administration discussions.
Ultimately, they decided to move up the timeline and have him announce his support during the ABC interview at the White House, the official said. And a top Democrat told CNN that Obama knew the issue would come up at the convention -- partly because of a push for support for same-sex marriage to be included in the Democratic Party platform -- and in debates.
Obama, explaining to ABC how his position has evolved, noted that his daughters Malia and Sasha have "friends whose parents are same-sex couples. It wouldn't dawn on them that somehow their friends' parents would be treated differently. And frankly that's the kind of thing that prompts a change of perspective -- not wanting to somehow explain to your child why somebody should be treated differently when it comes to the eyes of the law."
Asked about whether his new position is a calculated move in an election year, Obama said it would "be hard to argue that somehow this is something that I'd be doing for political advantage. Because frankly, you know, the politics -- it's not clear how they cut."
The interview with ABC aired the same day Obama will attend a fundraiser in Los Angeles, where support for same-sex marriage is strong. Movie star George Clooney is hosting the event, which is raking in $15 million, according to a top Democratic source. On Monday, openly gay singer Ricky Martin is hosting a fundraising event for Obama in New York.
The president told ABC he won't spend much time talking about the issue, because he's focused on the economy.
News of Obama's history-making decision on same-sex marriage broke Wednesday when the interview was taped.
"At a certain point I've just concluded that for me, personally, it is important for me to go ahead and affirm that I think same-sex couples should be able to get married," Obama said.
He previously opposed such marriages.
"I had hesitated on gay marriage, in part, because I thought civil unions would be sufficient," the president said. "I was sensitive to the fact that -- for a lot of people -- that the word marriage is something that provokes very powerful traditions and religious beliefs."
But Obama said his thinking shifted as he witnessed committed same-sex marriages and thought about U.S. service members who were "not able to commit themselves in a marriage."
In 2011, the Pentagon stopped enforcement of the "don't ask, don't tell" policy on gays and lesbians serving in the military. That change played a part in Obama's announced stance on same-sex marriage.
"When I think about those soldiers or airmen or Marines or sailors who are out there fighting on my behalf and yet feel constrained, even now that 'don't ask, don't tell' is gone, because they are not able to commit themselves in a marriage, at a certain point I've just concluded that for me personally it is important for me to go ahead and affirm that I think same-sex couples should be able to get married," he told ABC.
The announcement puts Obama squarely at odds with presumptive Republican presidential nominee Mitt Romney, who said during an appearance Wednesday in Oklahoma, "I believe marriage is a relationship between a man and a woman."
In comments Wednesday to CNN Denver affiliate KDVR-TV, Romney reiterated his opposition to same-sex marriage.
"And I do not favor civil unions if they are identical to marriage other than by name," Romney said during a visit to Fort Lupton, Colorado. "My view is the domestic partnership benefits, hospital visitation rights and the like are appropriate, but that the others are not."
The issue is a divisive one in American politics, but it's uncertain how the development might play out at the voting booth.
A Gallup Poll released Tuesday indicated 50% of Americans believe same-sex marriages should be recognized by law as valid, with 48% saying such marriages should not be legal -- a dramatic shift from a few years ago. A Gallup poll in 2009 found 40% supported same-sex marriage and 57% were opposed.
But a CNN/ORC International poll, taken in late March, indicated policies toward gays and lesbians were tied for last in people's opinions of the most-important issues facing the country.
Obama said he was "disappointed" by this week's vote on the issue in North Carolina, which he described as discriminatory against gays and lesbians, a spokesman said earlier Wednesday.
North Carolina on Tuesday voted to implement a state constitutional ban on same-sex marriage, which was already prohibited by state law. Supporters of the measure pushed for the constitutional amendment, arguing that it was needed to ward off future legal challenges.
The president said he supports states deciding the issue on their own.
What's next for North Carolina?
The conservative Family Research Council criticized Obama. The group's president said the decision will aid Romney.
"The president, I think, has handed to Mitt Romney the one missing piece in his campaign," said Tony Perkins, the council's president. "That is the intensity and motivation that Mitt Romney needs among social conservatives to win this election."
An expert on religion and politics said the move will make "an already close election even closer."
"It cuts both ways -- it activates both Democratic and Republican base voters," said John Green of the University of Akron.
Obama told ABC that some opinions on the issue are "generational."
"When I go to college campuses, sometimes I talk to college Republicans who think that I have terrible policies on the economy, on foreign policy, but are very clear that when it comes to same-sex equality or, you know, sexual orientation, that they believe in equality," he said.
The new president of the Human Rights Campaign, the largest group representing gay, lesbian, bisexual and transgender Americans, lauded the development.
"President Obama's words today will be celebrated by generations to come," Chad Griffin said in a statement Wednesday.
Griffin later told CNN that he believes "we will never have another president, Democrat or Republican, that opposes gay marriage."
Same-sex marriage foe Bill Donohue, president of the Catholic League, told CNN "a child needs a mother and father."
Rep. Barney Frank, a gay Democrat from Massachusetts, said that "no president could have done this 10 years ago."
Before Tuesday's North Carolina referendum, 30 states had voted in favor of constitutional amendments that seek to defend traditional definitions of marriage as a heterosexual union.
Six states -- Massachusetts, Connecticut, Iowa, Vermont, New Hampshire and New York -- and the District of Columbia issue marriage licenses to same-sex couples.
In February, Washington Gov. Christine Gregoire signed a bill that would legalize same-sex marriage beginning in June, but opponents there have pledged to block the bill and called for voters to decide the issue.
Maryland Gov. Martin O'Malley signed into law a bill that permits the state's same-sex couples to wed as of January 1, and state residents may vote to affirm such a law. Minnesota will vote on a state constitutional amendment similar to the one in North Carolina. Maine will have a referendum on allowing same-sex marriage.
Legal challenges over same-sex marriage could reach the U.S. Supreme Court in coming months, but it seems unlikely justices would hear arguments before Election Day.
The issue is on two legal tracks.
The 9th U.S. Circuit Court of Appeals will decide the constitutionality of California's Proposition 8, a voter-approved measure that would recognize marriage only between one man and one woman. A federal judge earlier struck down the law as a violation of equal protection, prompting the current appeal.
The Obama administration announced last year it believed the Defense of Marriage Act, often referred to as DOMA, to be unconstitutional. The law defines marriage for federal purposes as unions only between a man and woman.
A federal appeals court in Boston last month heard a DOMA lawsuit by a same-sex couple in Massachusetts. At issue is whether the federal government can deny tax, health and pension benefits to same-sex couples in states where they can marry.
That federal law is being officially defended in court by House Republicans, led by Speaker John Boehner, R-Ohio, who stepped in after the Justice Department refused to participate.