"If Republicans succeed in repealing the ACA, health care costs will explode, Americans in the individual market will see their premiums double by 2026, and the number of uninsured Americans will surge by 18 million in the first year alone and by 32 million by 2026," said House Democratic Leader Nancy Pelosi.
What the CBO looked at was a bill approved by Republicans in 2015, and vetoed by President Obama early in 2016, which would have repealed large chunks of the Obama health law - H.R. 3762, the Restoring Americans’ Healthcare Freedom Reconciliation Act.
The report also comes a day before testimony by Mr. Trump's pick to run the Department of Health and Human Services, as Rep. Tom Price (R-GA) has been at the forefront of GOP efforts to repeal and replace the Affordable Care Act.
Supporters of Mr. Trump did their own work on social media to push back against the CBO report, with some painting it as fake news.
Whatever you think of the report and its conclusions, the quick firestorm it created is a reminder of just how animated the health care debate will be on Capitol Hill.
Republicans have said they will unveil plans in coming weeks for how best to ensure that millions have health insurance coverage.