How Hillary Clinton Is Showing Solidarity for Same-Sex Couples on Big Supreme Court Day

— -- Just hours before the U.S. Supreme Court is set to hear historic oral arguments that could legalize same-sex marriage nationwide, Hillary Clinton has taken to social media to make her stance clear.

In a sign of solidarity, the Democratic presidential candidate this morning tweeted her support of same-sex marriage, saying that "every loving couple and family deserves to be recognized and treated equally under the law." She also changed both her Twitter and Facebook avatars to a rainbow-themed version of her campaign slogan.

Clinton recently shifted her position on the issue of same-sex marriage slightly.

Last summer, in a testy interview with NPR's Terry Gross, Clinton said while she supports same-sex marriage, the issue "had always been a matter left to the states." In a statement released via a spokeswoman earlier this month, Clinton now said she hopes it would become a "constitutional right."

“Hillary Clinton supports marriage equality and hopes the Supreme Court will come down on the side of same-sex couples being guaranteed that constitutional right,” Hillary for America spokeswoman Adrienne Elrod said in a statement to ABC News.

Today's tweet from Clinton comes the same day the justices are meeting to begin laying out their own stances on the issue.

The court will hear extended arguments, set to last roughly 2 1/2 hours, about whether same-sex marriage bans are constitutional, and whether states that do not permit same-sex marriage must nonetheless recognize such unions from elsewhere.

The Associated Press contributed to this report.