Agencies like NASA and the Environmental Protection Agency were being nearly shuttered. People classified as essential government employees — such as air traffic controllers, Border Patrol agents and most food inspectors — will continue to work.
The White House was operating with a skeletal staff, including household workers taking care of the first family's residence and presidential aides working in the West Wing. A groundskeeper working outside Tuesday morning at daybreak said he was doing the job normally handled by four workers.
Given the shutdown, White House officials were discussing whether President Barack Obama should change plans for a trip to Asia scheduled to begin Saturday.
The military will be paid under legislation freshly signed by Obama, but paychecks for other federal workers will be withheld until the impasse is broken. Federal workers were told to report to their jobs for a half-day but to perform only shutdown tasks like changing email greetings and closing down agencies' Internet sites.
The self-funded Postal Service will continue to operate and the government will continue to pay Social Security benefits and Medicare and Medicaid fees to doctors on time.
On Capitol Hill, lawmakers get to decide which of their staff members keep working and which are furloughed. Members of Congress will continue getting paid.
The Senate twice on Monday rejected House-passed bills that first sought to delay key portions of the 2010 "Obamacare" law, then to delay the law's requirement that millions of people buy medical insurance. The House passed the last version again early Tuesday naming negotiators for a Senate-House conference on the bill; Senate Majority Leader Harry Reid said the same fate awaits that measure when the Senate reconvenes Tuesday morning.
"You don't get to extract a ransom for doing your job, for doing what you're supposed to be doing anyway, or just because there's a law there that you don't like," Obama said Monday, delivering a similar message in private phone calls later to Republican House Speaker John Boehner and other lawmakers.