Washington (CNN) -- With two weeks and counting until the federal government runs out of money, President Barack Obama is turning up the heat on a group of congressional Republicans threatening to shut down the government over their opposition to the health care law.
But the president's comments on Monday came as new polling indicates that Affordable Care Act, better known as "Obamacare," is becoming more unpopular with Americans.
"I cannot remember a time when one faction of one party promises economic chaos if it can't get 100% of what it wants. That's never happened before but that's what's happening right now," Obama said at an event at the White House that marked the fifth anniversary of the 2008 financial crisis.
"You have some Republicans in the House of Representatives who are promising to shut down the government at the end of the month if they can't shut down the Affordable Care Act. And if that scheme doesn't work, some have suggested they won't pay the very bills that Congress has run up, which would cause America to default on its debt for the first time in its history," Obama said.
Current federal spending is set to expire on September 30 -- the end of the fiscal year -- setting up another budget battle between congressional Republicans and the White House.
That deadline occurs one day before a key element of the health car law takes effect. Enrollment in state insurance exchanges that form the core of the new law begins on October 1.
GOP leaders in Congress continue to call for a repeal of the 2010 law.
"For the sake of our economy, we will continue to do everything we can to repeal, dismantle, and defund Obamacare," House Speaker John Boehner said last week.
But some conservative lawmakers, backed by some tea party and other grassroots conservative groups, want to go a step further.
They're using the budget battle as leverage, vowing to oppose any measure that provides funding for the federal government from including money for the health care law.
And they're putting pressure on GOP leaders in Congress as well as the White House.
"We need some backbone up here; we need some help. We don't need to be the invertebrate caucus. We need to be the caucus with a spine, with a heart, and with the will to defund Obamacare," Sen. Rand Paul of Kentucky said last week at a defund Obamacare rally on Capitol Hill.
In addition to the spending deadline and a possible shutdown, the White House and congressional Republicans also appear to be headed toward a showdown over raising the nation's $16.7 trillion debt ceiling. The government could hit its limit on borrowing to pay its bills sometime around mid-October to early November.
Obama said if Republicans force a shutdown it would be the "height of of irresponsibility."
Organizing for Action, the nonprofit grassroots advocacy group formed from the remnants of the president's 2012 re-election campaign, says its running a commercial on national cable TV starting Tuesday for a week that lays blame with House Republicans.
A national poll conducted earlier this month indicates congressional Republicans would shoulder more blame than Obama if there's a shutdown. According to a CNN/ORC International survey, a third would consider the president responsible for a shutdown, with 51% pointing a finger at the GOP in Congress, up from 40% who felt that way earlier this year.
"The Affordable Care Act has been the law for three and a half years now. It passed both Houses of Congress, the Supreme Court ruled it constitutional. It was an issue in last year's election and the candidate who called for repeal lost," Obama said in defense of the signature domestic achievement of his presidency.
But new polling suggests that the law is losing support among Americans.
Forty-two percent of people questioned in a USA Today/Pew Research Center poll released Monday said they approve of the measure, down from 47% in the summer of 2012, soon after the law was upheld by the Supreme Court.
It's a similar story in an NBC News/Wall Street Journal poll also released Monday. Forty-one percent of those surveyed call the health care law a bad idea, with 31% saying it's a good idea. And by a 45%-23% margin, the public says the measure will have a negative impact on the country's health-care system. Three in 10 say the law will have a negative impact on their families, with just 12% saying it will help them and more than half saying the new measure won't impact them one way or another.
The surveys from NBC News/Wall Street Journal and the Pew Research Center are in line with a CNN/ORC poll from last week which indicated a 12-percentage point drop in support for all or some of the provisions in the law, from 51% at the beginning of the year to 39% now.
The new health care polling may only embolden conservatives pushing to defund Obamacare, and with two weeks and counting, possibly hurting changes for any bipartisan agreement to avoid a government shutdown.