Dr. David Cull, a prominent vascular surgeon in Greenville, had invented a small valve system that, if it works, could spare 300,000 dialysis patients across the country enormous suffering and save U.S. taxpayers billions of dollars.

But Cull’s hometown senator, Jim DeMint, would not write a letter supporting the surgeon’s application for a federal grant under the landmark health care bill that President Barack Obama signed into law a year ago today.

A hard-core conservative with a growing national following, DeMint vowed in 2009 to make health care Obama’s “Waterloo” and is leading Republican efforts in Congress to repeal or deny funding to the law, designed to provide medical coverage to 31 million uninsured Americans.

Backing a grant application under the law — even for a constituent who lives in the same Upstate town as DeMint — would leave the senator open to charges of hypocrisy, staffers say.

“Senator DeMint opposed President Obama’s government takeover of health care because he believed it would lead to higher insurance premiums, less choices for patients, and that it was unconstitutional,” said DeMint spokesman Wesley Denton. “And that’s exactly what has happened.”