For three years, the Obama administration has been preparing for this moment: the launch of new insurance exchanges, intended to expand health coverage to millions of uninsured Americans.
But this is far from the grand opening that President Barack Obama may have expected.
Instead, the exchanges are starting up just as most of the federal government is shutting down, left unfunded by a Congress that's still bitterly divided about whether to discard Obama's health care law altogether.
There will be just a skeletal staff at the White House on Tuesday when Obama appears in the Oval Office to tout the benefits of his law alongside Americans who plan to purchase insurance through the exchanges. Many of Obama's aides, like hundreds of thousands of federal workers across the country, will be on furlough due to the first partial shutdown in almost two decades.
(Read more: The selling of Obamacare: Reaching the uninsured)
"Unfortunately, Congress has not fulfilled its responsibility," Obama said in a video message the White House released just after midnight Tuesday, as Congress missed its deadline to keep the government running. "It has failed to pass a budget and, as a result, much of our government must now shut down until Congress funds it again."