Senate Republican's health-care reform bill is worse than the House version, Democratic Sen. Heidi Heitkamp told CNBC on Monday.

The North Dakota senator said the GOP health bill is not an Obamacare replacement but "entitlement reform." Nothing in the new bill "adds up," she said.

"You have to look at it from a mile high and they're trying to tell you we're going to keep coverage the same, no one's going to get hurt, and we're going to take billions of dollars out of health care," Heitkamp said on "Squawk Box."

"Once it's parsed and people have a chance to look at it, it is only going to get more difficult," she added.

At least five Republican senators have announced public opposition to the Senate GOP plan as of Monday morning, with some claiming the bill does nothing to deal with rising health-care costs. To assure passage, Republicans cannot lose more than two GOP votes.

Still, Heitkamp said: "I never bet against Mitch McConnell. I think you're a fool if you do."

Heitkamp spoke a day after President Donald Trump said congressional Republicans are not "that far off" on a replacement for the Affordable Care Act, better known as Obamacare.

Senate Republicans, led by McConnell, released the Senate health bill on Thursday, proposing a phase out of Medicaid's expansion program and cap on Medicaid spending, a repeal of Obamacare taxes and restructuring subsidies to insurance customers.