Obama administration attorneys successfully argued that the individual mandate portion of the law is a tax, not a mandate, to convince the judges that the law is constitutional. That argument worked for the court but could hurt Democrats with messaging on the law going forward.

"We are being burdened with the biggest permanent tax increase in our nation's history. This is a sad day," Rick Santorum said in a statement. "I believe so strongly that if we do not defeat President Obama this November and elect more conservatives in the House and Senate, our country's future prosperity is at risk."

That sentiment was echoed by other Republicans.

"This November the American people have an opportunity to choose new leadership in Washington who will listen to their voices and repeal this costly, harmful government health care law," former Sen. George Allen (R-Va.), who is running for his old seat, said in a statement. "I want to be the deciding vote to repeal this health care law."

Senate candidate and former Rep. Mark Neumann (R-Wis.) agreed.

"Now more than ever it will take a conservative United States Senate to repeal ObamaCare. The Supreme Court's faulty decision today means we have to elect conservatives to the Senate this fall to end ObamaCare and eliminate the individual mandate," he said in a statement. "Today is just another chapter on ObamaCare, but it is not the end of the story. This ends next year when a conservative Senate repeals it."

Steven Law, president and CEO of American Crossroads, addressed the affect it would have the election, noting "this decision will drive Republican voter intensity sky-high."

He added that "the last time Obamacare was litigated in a general election, Republicans picked up an historic number of seats in the U.S. House and made big gains in the U.S. Senate."