The current battle focuses on expiring subsidies for the Affordable Care Act that Democrats say will hurt the ability of millions of enrolees to afford insurance. Democrats have also said they want to reverse Medicaid cuts that Trump signed into law this summer.

Republicans are seeking a bill to temporarily extend federal spending at current levels without any add-ons.

If the government shuts down, President Donald Trump and his administration – which has already defied norms on executive power – likely will seek to exert more power.

Trump’s Office of Management and Budget under Russell Vought has moved with more executive authority over spending, which is typically left to Congress. The administration took steps to cancel foreign aid and asserted power to withhold billions in domestic spending.

“I would expect this shutdown to look different than any other shutdown,” said Joshua Sewell, Taxpayers for Common Sense director of research and policy. He said he expects that the Trump team’s actions would be guided by what they believe achieves the most for them politically.

Trump could use a shutdown to dismantle government functions, wrote Max Stier, chief executive of the Partnership for Public Service, a nonprofit focused on improving the federal government.

If lawmakers can’t reach a deal, Stier wrote, Trump and Vought “will have enormous latitude to determine which services, programmes and employees can be sidelined – decisions that could go far beyond what has occurred during past shutdowns”.

Beyond the Antideficiency Act, which says the government cannot spend money or incur debts without Congress’s authority, the shutdown process has historically been guided by traditions, not laws.

In recent past shutdowns, hundreds of thousands of employees were furloughed, but the shutdowns did not result in mass permanent layoffs or significant reorganisations. Under federal law, federal workers also receive back pay for their time on furlough.

Trump and his congressional allies would be in charge of the government amid a shutdown. What could Trump do on his own?