President Obama on Saturday vowed that Obamacare is “going to work,” even as GOP lawmakers pushed efforts to defund the healthcare law at the risk of a government shutdown.

“The Affordable Care Act is 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,” said Obama in his weekly address.

On Tuesday, Oct. 1, consumers can begin enrolling in the law’s new insurance exchanges. Obama encouraged those without healthcare to visit the online sites which will provide information about plans.

“Nearly 6 in 10 uninsured Americans will be able to get coverage for $100 or less,” said Obama, touting the law’s benefits.

But Obama also sharply criticized Republicans, as lawmakers struggle to pass a spending bill to avert a government shutdown on Tuesday. Conservative lawmakers are demanding that any spending bill also defund Obamacare.

The House last week passed a bill which strips funding for the healthcare law. The Democratically-controlled Senate sent back a stopgap spending bill leaving Obamacare untouched, but Speaker John Boehner, R-Ohio, has said it's unlikely that would pass the House.

“Republicans in Congress are threatening to shut down the government – or worse – if I don’t agree to gut this law,” said Obama.

“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,” the president added. “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.”

Obama also warned Republicans that he would not negotiate over raising the nation’s borrowing limit in mid-October. GOP lawmakers hope to tie a hike in the debt limit to further spending cuts and entitlement reforms.

“The American people have worked too hard to recover from crisis to see extremists in their Congress cause another one,” said Obama.