The US Senate has extended its debate on President Donald Trump's controversial budget, with the expectation of voting on the plan, which would add more than $5 trillion to the public debt.
Republicans told the media that the "vote-a-rama" would begin at 9am local time on Monday (11pm AEST), the process in which lawmakers present amendments to the initiative, which contains key elements of Trump's agenda, such as tax and public spending cuts, and increased funding for defence and immigration control.
It is still uncertain whether all 53 senators from Trump's party will support the bill, as it would add $US3.3 trillion ($A5.1 trillion) to the public debt within 10 years, the Congressional Budget Office (CBO) now estimates, a higher estimate than the $US2.4 ($A3.7) trillion in the version approved by the House in May.
Other lawmakers question the cuts to social programs such as Medicaid and food stamps because the CBO predicts that 12 million people will lose their health insurance by 2034 under the initiative, which would cut $US1.1 trillion ($A1.7 trillion) in public health policies.
Among the critics is Republican Senator Thom Tillis of North Carolina, who resigned from his re-election bid on Sunday after publicly opposing the bill and drawing criticism from Trump.
"Facts matter, people matter. The Senate's approach to Medicaid breaks promises and will push people who truly need it off Medicaid," the lawmaker said.
Elon Musk, also took a swipe at the bill, which would end tax breaks for the electric vehicles that his automaker Tesla manufactures, posting on X it was "utterly insane and destructive" and "political suicide for the Republican Party".
Meanwhile, Democrats displayed unified opposition by first forcing 16 hours of reading aloud of the 940-page bill and then exhausting the 10 hours of debate allotted to each party to delay the process and highlight the tax cuts for the wealthy and the budget.
"Democrats are exposing on the floor through parliamentary inquiries the hypocrisy of what Republicans are trying to do here in the Senate. We are exposing how Republicans are trying to hide the true cost of their gifts to billionaires," Democratic leader Chuck Schumer said.
Trump intensified his lobbying in the last week to get the Senate to approve his controversial "Big, Beautiful Bill" for signing by Friday, Independence Day.
The controversy grew this week after the release of the 940-page draft currently being discussed by the Senate. It includes more cuts than those approved by the House of Representatives, particularly to social programs and tax incentives for wind and solar energy, and electric vehicles.