The bill is deeply unpopular - with nearly 2-to-1 opposition, according to a Washington Post-Ipsos poll conducted in June.

The legislation, which extends tax cuts and funds border and defense programs, would increase the national debt by close to $4 trillion over the next decade.

The GOP megabill has new tax breaks aimed at low- and moderate-income households, and spending cuts that could make it harder for some to receive public assistance or hold onto health insurance.