Sen. Richard M. Burr on Thursday took aim at conservatives who have threatened to shut down the federal government if the 2010 health care law is not defunded, calling it the “dumbest idea I’ve ever heard.”

In an audio recording posted by Public Radio International’s Washington correspondent Todd Zwillich, the North Carolina Republican was asked by reporters if he was supportive of the efforts led by GOP Sens. Mike Lee of Utah and Marco Rubio of Florida.

“That’s the dumbest idea I’ve ever heard of,” Burr said. “As long as Barack Obama is president, the Affordable Care Act is going to be the law.”

One reporter — we suspect The Associated Press’ Andy Taylor — noted Burr was in the House during the 1995 government shutdown that proved disastrous for Republicans.

“I was around in 1995,” Burr acknowledged. “Some of these guys need to understand that if you shut down the federal government, you’d better have a specific reason to do it that’s achievable. Defunding the Affordable Care Act is not achievable through shutting down the federal government.”

A dozen GOP senators signed a letter to Senate Majority Leader Harry Reid, D-Nev., vowing to oppose any spending bill that failed to defund Obamacare, including Rubio, Lee, Ted Cruz of Texas, Jim Risch of Idaho, Rand Paul of Kentucky,  James M. Inhofe of Oklahoma, David Vitter of Louisiana, John Thune of South Dakota, Jeff Chiesa of New Jersey, Michael B. Enzi of Wyoming, Deb Fischer of Nebraska and Charles E. Grassley of Iowa.

The letter follows:

Dear Leader Reid:

We view the Obama Administration’s recent decision to delay ObamaCare’s employer mandate and eligibility verification for the individual exchanges as further proof the law is a failure that will inevitably hurt businesses, American families, and the economy.

In light of this admission, we believe the only way to avert disaster is to fully repeal ObamaCare and start over with a more sensible, practical approach to reforming our healthcare system.

However, if Democrats will not agree with Republicans that ObamaCare must be repealed, perhaps they can at least agree with the president that the law cannot be implemented as written.  If the administration will not enforce the law as written, then the American people should not be forced to fund it.

This is a matter not only of fiscal prudence, but of fundamental fairness as well. The president cannot seriously expect to waive ObamaCare’s onerous mandates on large businesses, while simultaneously forcing individuals and families to pay to implement an individual mandate the public has opposed since before the law was even passed.

For these reasons, we will not support any continuing resolution or appropriations legislation that funds further implementation or enforcement of ObamaCare.