President Barack Obama says Republicans on an "ideological crusade" to kill his signature health care program are responsible for the U.S. government shutdown that began Tuesday.
On the day when the U.S. government closed all but essential services, Mr. Obama vowed not to give in to what he called "reckless demands" to deny affordable health insurance to millions of Americans.
He said that closing down the government accomplished nothing because Obamacare is the law of the land, passed by Congress, supported by voters and upheld by the Supreme Court.
The government started closing down at midnight Monday, after the Democratic-controlled Senate rejected spending bills by the Republican-led House that would have delayed or killed Obamacare.
Republican opponents to Obamacare say it forces people, including small businesses, to buy expensive insurance policies against their will, hurting the economy.
President Obama said if Republican House Speaker John Boehner had allowed a simple vote on a spending bill -- one without any other issues attached to it -- it would have passed the House and Senate and the government would have stayed open.
About 800,000 federal workers are now on furlough. Other federal workers are staying on the job with no guarantee when they will be paid.
The shutdown will not affect Voice of America broadcasts, but it has closed national parks and other services such as federal tax offices, help for veterans, and food aid for the poor. Most civilian employees at the Pentagon must stay home and the U.S. space agency is almost entirely shut down.
The U.S. military will remain on duty, and ongoing military operations like those in Afghanistan will continue.
Experts say a shutdown of more than two weeks is likely to slow the U.S. economy because of reduced tourism and furloughed federal workers cutting back on their spending.