U.S. Sen. Al Franken said opponents of the Affordable Care Act (ACA) raised a "ridiculous" argument at the Supreme Court Wednesday when they told the justices that the nation's health care reform law does not allow premium-lowering tax credits in 34 states where the federal government runs insurance exchanges.

"I was actually there when the law was written and passed," Franken told a press conference after the oral arguments. "I know what our intention was."

It was not, the Minnesota Democrat said, to exclude millions of Americans from health insurance coverage by denying them subsidies needed to afford policies. Franken accused ACA opponents of seizing on a few words in a 2,200-page bill to "reverse engineer" an argument that would kill the entire law.

The health law does say that premium subsidies are available to state-run exchanges. But it also says that the federal government will operate exchanges in states that refuse to form them. Subsidies, mandatory participation and coverage of pre-existing conditions are the three-legs of the legislative stool that support health reform. Getting rid of any of them will undermine the rest, most experts agree.

Joining Franken at the press conference were Democratic Sen. Chris Murphy of Connecticut and premium tax credit beneficiaries Bonita Johnson of Detroit and Terry Donald of St. Petersburg, Fla. Johnson and Donald receive premium subsidies from federally run exchanges. Johnson said her health insurance would cost four times as much without subsidies and no longer be affordable. Donald, whose wife has cancer, said his insurance would be six times as much and he would have to drop coverage.

"This was not anyone's thinking" when the health care law passed in 2010, Franken said.