President Obama publicly announced his support for gay marriage last year on May 9 in an ABC interview. His views on same-sex marriage evolved continually over the years, but he became the first sitting president to endorse the issue.
"As I've said, I’ve been going through an evolution on this issue. I've always been adamant that gay and lesbian Americans should be treated fairly and equally...And I had hesitated on gay marriage in part, because I thought civil unions would be sufficient," he said in 2012. In February of this year he said that banning gay marriage at any level—federal or state—is unconstitutional.
Since Obama's comments, Democratic and Republican politicians—as well as American voters—have vocally expressed their support of gay marriage. Former Florida governor Charlie Crist this week became the latest politician to endorse the idea. Crist switched from Republican to Independent to Democrat in just two years.
Take a look at the evolution of the support for same-sex marriage since Obama's comments the past year:
Delaware on Tuesday became the 11th state to allow marriage equality when Gov. Jack Markell signed the bill into law. The push for gay marriage in Delaware followed the passage of a similar laws in Rhode Island, Maine, Maryland, and Washington last November.
Illinois GOP Chairman Pat Brady announced his support for same-sex marriage legislation before the state legislature in January. He resigned as leader of the state party on Tuesday after facing heat from the more conservative wing of his party for months.
NBA center Jason Collins became the first male athlete actively playing in a major pro-sport to come out as gay. He made the announcement in April 2013. He most recently played for the Washington Wizards but was previously with the Boston Celtics.
In a controversial resolution released last month, the Boy Scouts of America proposed lifting its ban on gay Scouts—while continuing to prohibit gay adult leaders.
The Supreme Court heard arguments in March for and against Proposition 8, a California law that bans same-sex marriages, and the Defense of Marriage Act (DOMA), a federal law defining marriage as between a man and a woman. A decision might not be made until June. Former President Bill Clinton signed DOMA into law in 1996 during his re-election campaign, but publicly opposed the legislation in March 2013. Former Secretary of State Hillary Clinton also came out in favor of gay marriage this year.
Fifty-eight percent of registered American voters said they agree with marriage equality and believe same-sex marriage should be legal, according to an ABC News/Washington Post poll from March. The statistic is a dramatic change from the 32% of registered voters who supported same-sex marriage in a similar 2004 survey.
Ohio's Republican Sen. Rob Portman in March reversed his anti-gay marriage position. Portman attributed his change of heart to his family, two years ago, the Republican senator's son told him he was gay. He is one of four Republicans in Congress who support gay marriage.
Celebrities and politicians including actor George Takei and Maryland's Democratic Gov. Martin O'Malley, replaced personal Facebook profile pictures with the Human Rights Campaign's red logo in March. Even more spoke out on Twitter.
In February 2013, more than two dozen Republicans added their names to a brief urging the Supreme Court to declare that gay couples have a constitutional right to marry.
Americans for the first time approved gay marriage at the ballot box in November 2012. Voters in Maine and Maryland approved ballot initiatives to begin allowing same-sex unions; citizens in Minnesota declined to back an initiative that would have enshrined in the state's constitution a definition of marriage as solely a union between one man and one woman; and nearly 52% of Washington voters said they supported same-sex marriage.
Tammy Baldwin made history on Election Day when Wisconsin elected her as the nation's first lesbian senator in November 2012.
Democratic Representative Barney Frank became the first sitting congressman to enter into a same-sex marriage when he wed his longtime partner last July. The Democrat from Massachusetts in 1987 became the first sitting member of Congress to say that he was gay.
The Democratic hold-outs on gay marriage include Arkansas Sen. Mark Pryor, West Virginia Sen. Joe Manchin, and Louisiana Sen. Mary Landrieu. The Republican National Committee voted unanimously to uphold marriage as one man and one woman at its annual spring meeting last month. Republican House Speaker John Boehner said this year that he doesn't think his opinion about same-sex marriage will ever change.