Surprising many conservatives, former House Speaker Newt Gingrich stirred a lively debate Sunday by slamming Rep. Paul Ryan's plan to reform Medicare on NBC's "Meet the Press."

In what one popular conservative website described as Gingrich "tacking left," the now-declared presidential candidate dismissed a plan popular among many conservatives as "radical change" that he suggested was dangerous for Republicans to embrace heading into an election year.

The House budget chairman's plan is designed to move to a system where seniors receive vouchers to buy private insurance. It has been endorsed by the majority of House Republicans.

But Gingrich said it was "too big a jump. I think what you want to have is a system where people voluntarily migrate to better outcomes, better solutions, better options."

"I'm against Obamacare, which is imposing radical change, and I would be against a conservative imposing radical change," he continued.

"I don't think right-wing social engineering is any more desirable than left-wing social engineering," Gingrich said. "I don't think imposing radical change from the right or the left is a very good way for a free society to operate."

Gingrich has instead called for a system that would preserve the current Medicare program alongside a voluntary, privatized version. But nothing he has said came close to the blast he unleashed on his own party's top priority in Congress.

"There are specific things you can do," Gingrich explained to NBC's David Gregroy. " At the Center for Health Transformation, which I helped found, we published a book called "Stop Paying the Crooks." We thought that was a clear enough, simple enough idea, even for Washington. We--between Medicare and Medicaid, we pay between $70 billion and $120 billion a year to crooks.

And IBM has agreed to help solve it, American Express has agreed to help solve it, Visa's agreed to help solve it. You can't get anybody in this town to look at it. That's, that's almost $1 trillion over a decade. So
there are things you can do to improve Medicare."

Ryan, meanwhile, defended it during an appearance on the CNN program "State of the Union."

"We have got to reform this program for the next generation if we're going to save it for the next generation and that's what we're proposing to do," the Wisconsin Republican said.

Ryan's spokesman Conor Sweeney took issue with Gingrich calling the plan "radical", saying the Ryan budget "remains the only serious proposal put forward on either end on Pennsylvania Avenue that saves Medicare."

"The solutions offered by Chairman Ryan and House Republicans make no changes to Medicare for those in and near retirement, while offering a strengthened, personalized program that future generations can count on when they retire," Sweeney told National Review Online's Robert Costa.

"Far from claims of radicalism, the gradual, common-sense Medicare reforms ensure that no senior will be forced to reorganize their lives because of government's mistakes. The most 'radical' course of action on Medicare is continue to cling to the unsustainable status quo," Sweeney said.