In his weekly radio and Internet address Saturday, the president said people who already have healthcare coverage are receiving benefits under ACA -- commonly known as Obamacare -- that they did not receive before it was enacted in 2010, and people without health insurance will be able to buy it beginning Oct. 1.
"It's the day a big part of the Affordable Care Act kicks in, and tens of millions of Americans will finally have the same chance to buy quality, affordable healthcare as everyone else," he said. "It's also the day that a group of far-right Republicans in Congress might choose to shut down the government and potentially damage the economy just because they don't like this law."
Obama called the Affordable Care Act "one of the most important things we've done as a country in decades to strengthen economic security for the middle class and all who strive to join the middle class. And it is going to work.
"That's also one of the reasons it's so disturbing that Republicans in Congress are threatening to shut down the government -- or worse -- if I don't agree to gut this law," the president said.
"Congress has two responsibilities right now: pass a budget on time, and pay our bills on time," he said.
"If Congress doesn't pass a budget by Monday -- the end of the fiscal year -- the government shuts down, along with many vital services the American people depend on," Obama said. "On Friday, the Senate passed a bill to keep the government open. But Republicans in the House have been more concerned with appeasing an extreme faction of their party than working to pass a budget that creates new jobs or strengthens the middle class. And in the next couple days, these Republicans will have to decide whether to join the Senate and keep the government open, or create a crisis that will hurt people for the sole purpose of advancing their ideological agenda.
"Unfortunately some Republicans have suggested that unless I agree to an even longer list of demands -- not just gutting the healthcare law, but things like cutting taxes for millionaires or rolling back rules on big banks and polluters -- they'll push the button, throwing America into default for the first time in history and risk throwing us back into recession," the president said.
He said he will work with "anyone who wants to have a serious conservation about our economic future. But I will not negotiate over Congress' responsibility to pay the bills it has already racked up."
Obama urged his audience to visit HealthCare.gov "to find what's called the health insurance marketplace in your state" and to "spread the word" that the marketplaces "will be open for business on Tuesday, no matter what."
Celebrity Couples of 2014 [PHOTOS]