White House press secretary Sean Spicer told reporters Wednesday that it was "literally impossible" to predict the effects of the bill House Republicans are advancing to repeal and replace Obamacare.

The bill, the American Health Care Act, may receive a vote this week. Democrats and other critics have said they are concerned about how lawmakers plan to move forward on the bill without submitting it for a score to the Congressional Budget Office, the nonpartisan branch that would make a projection about how the legislation affects insurance rates and federal spending.

The most recent changes to the bill would allow states to apply for waivers to opt out of various Obamacare requirements, as long as they set up additional federal funding for people with pre-existing conditions or high medical costs. Several centrist Republicans have said they oppose those provisions or are worried about cuts to the Medicaid program.