The bill contains too many unknowns for the office to successfully predict its effects, Deputy Press Secretary Sarah Sanders said.
"I think even if they were to score it, it is impossible to score a lot of the things that would go into this, because it has so many different factors that you simply can't predict: what governors may do in their states, specific conditions that patients may have," she said. "So even if it was to be scored, I think it would be impossible to predict how that might actually affect and impact."
As originally introduced in March, the GOP health care replacement bill would leave 24 million fewer people insured by 2026 than under Obamacare, CBO said. The legislation has been altered since then, but the CBO will not release a new report before the House vote on the bill Thursday.
A Texas Republican who practiced medicine for 25 years is confident the bill won't result in millions losing coverage due to less federal funding of Medicaid.
"The CBO coverage numbers were, to say the least, disappointing," Rep. Michael Burgess told CNN's Chris Cuomo Thursday on "New Day." But, he added, "I disagree with the derivation of some of the numbers. I don't think they accurately predicted human behavior."
Colorado Republican Mike Coffman said he remains a "no" because of not having a score and ongoing concerns about how the bill impacts those with pre-existing conditions.
"Also, as I have stated in the past, I'm certainly not going to vote on a bill of this magnitude that hasn't been fully scored by the Congressional Budget Office and whose estimated price tag is unknown," he tweeted.
Sen. Lindsey Graham, R-South Carolina, expressed concern about the process of the House vote.
"A bill -- finalized yesterday, has not been scored, amendments not allowed, and 3 hours final debate -- should be viewed with caution," the South Carolina Republican tweeted.
Another South Carolina lawmaker said he wished Republicans would slow down the process and said he is "certainly" concerned about voting on a bill without having an updated CBO score.
"That's why I was one of the hold outs in the first go around," Rep. Mark Sanford told CNN. "It has been a truncated process. I think it's not what a lot of us would have liked to have seen from a standpoint of a more robust debate, but we are where we are."
But House Freedom Caucus Chairman Mark Meadows dismissed the argument that Republicans are moving to fast trying to replace President Barack Obama's signature legislation.
"We've had some individual analysis that looks at those amendments on what it would do to make sure we're insuring more people," the North Carolina Republican said. "We believe the new CBO score will be a lot more attractive in terms of the number of people covered."
A Virginia lawmaker and economist argued that the additional amendments aren't going to dramatically change the CBO score and that the plan either expands coverage, lowers premiums or addresses pre-existing conditions.
"The basic CBO score will still be in the ballpark," Rep. Dave Brat told CNN. "So, every amendment added is a good move on policy grounds."
The conservative congressman said he isn't concerned about the optics of voting for a bill without having updated numbers on how many people it would impact.
"If you can get up right now in real time and explain to the American voter, just say, 'Hey, everything is going to move in a better direction' with a straight face, and I can say that, then there's no optic problem," Brat said.