President Barack Obama addressed the nation shortly after the decision was made, calling the ruling a victory for the country.
"This ruling is a victory for America," he said. "This decision affirms what millions of Americans already believe in their hearts. When all Americans are treated as equal, we are all more free."
The four Democratic candidates all expressed jubilation at the decision, echoing President Obama. There are 13 Republican candidates so far. Those that have released a statement largely expressed disapproval. Some said they believe that it is an issue that should be left to the states. Others said that they believe marriage should be defined as being between a man and a woman.
Here's a look at what the candidates are saying:
Democrats, approve
Hillary Clinton
Lincoln Chafee
Martin O'Malley
Bernie Sanders
Republicans, disagree
Jeb Bush
"I believe the Supreme Court should have allowed the states to make this decision."
Rick Santorum
Carly Fiorina
Rick Perry
Mike Huckabee
Donald Trump
Bobby Jindal
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Republicans, have not made statement
- Ben Carson
Rand Paul
Ted Cruz
George Pataki
Marco Rubio
Lindsey Graham