By Ashley Killough

CNN

WASHINGTON (CNN) -- The top Democrat on the Senate health committee is trying to keep a spotlight on Health and Human Services Secretary Tom Price's statement that nobody "will be worse off financially" under the Republicans' health care proposal.

Sen. Patty Murray of Washington state is sending a letter to the HHS secretary on Tuesday that goes after him on that promise, now that the nonpartisan Congressional Budget Office says that millions more will go uninsured under the Republican proposal.

She is requesting that he provide information and data on what made him say that, arguing that the claim "suggests a fundamental misunderstanding of the US health care system and the needs of those who rely on the (Affordable Care Act) reforms for coverage."

Murray also says in the letter that Price's comment "echoes promises made by President Trump and Republicans that simply do not square with rigorous, independent, publicly available analysis."

Asked in an interview Sunday on NBC's "Meet the Press" whether anybody would be worse off financially, Price cited rising premiums and said "there are a lot of people that are worse off right now when they're paying for health care and they aren't getting the care that they need."

He was pressed again on whether he could guarantee that people wouldn't be hurt financially.

"I firmly believe that nobody will be worse off financially in the process that we're going through," Price responded. "They'll have choices that they can select the kind of coverage that they want for themselves and for their family, not the government forces them to buy."

His comments came one day before the CBO estimated 24 million more Americans would be uninsured by 2026 if the Republican plan replaced Obamacare, including 14 million by next year.

CNN's MJ Lee contributed to this report.