President Barack Obama called the Supreme Court's landmark ruling upholding his health-care reform "a victory for people across the country."
Mitt Romney said he will work "on my first day as president" to repeal the law if he's elected in November.
They spoke Thursday shortly after the court, in a 5-4 decision, upheld the heart of the law.
"Today's opinion was a victory for people across the country," Obama said in the White House. He said it will make their lives more secure.
Minutes earlier, Romney sought to make the presidential race a referendum on the health-care law, saying: "If we want to get rid of Obamacare, we're going to have to replace Obama."
"Help us defeat Obamacare," Romney said, speaking in front of the U.S. Capitol.
"What the court did not do on last day in session, I'll do on my first day as president and act to repeal Obamacare."