(ABC News)

Rep. Paul Ryan said this morning on "This Week" that Chief Justice John Roberts had to "contort logic and reason" in order to rule the individual mandate - the most important part of President's Obama's signature health reform legislation - constitutional.

"I'm very disappointed in the ruling. I think the chief justice had to contort logic and reason to come up with this ruling," the Republican from Wisconsin said. "So one man decided against the dissenting opinion, against what I, you know, thought were his - his principles and judicial jurisprudence, he decided to leave this up to the American people. So now the stakes of this election could not be higher."

On Thursday, the United States Supreme Court ruled that the linchpin of President Obama's health care legislation - the individual mandate - was constitutional. Chief Justice John Roberts raised some eyebrows when he sided with the Supreme Court's four liberal members to write the majority opinion.

The ruling handed down declared the vast majority of the law constitutional, giving President Obama a major political victory as the presidential election draws near.

The ruling by the Supreme Court puts it at odds with the president, who told me in 2009 on "This Week" that "to say that 'you've got to take a responsibility to get health insurance' is absolutely not a tax increase."

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The GOP's response to the ruling was swift.

Presumptive Republican presidential nominee Mitt Romney, who passed health reform legislation in Massachusetts when he was governor that contained an individual mandate, said Thursday that he would attempt to repeal President Obama's health care reform if he wins the election this fall.

"Let's make clear that we understand what the court did and did not do. What the court did today was say that 'Obamacare' does not violate the Constitution," he said. "What they did not do was say that 'Obamacare' is good law, or that its good policy. 'Obamacare' was bad policy yesterday, it's bad policy today. 'Obamacare' was bad law yesterday, it's bad law today."

Ryan said this morning that he believes that a House vote to repeal President Obama's health care reform law will take place later this month.

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