(Image Credit: Jewel Samad/AFP/Getty Images)

With a possible government shutdown looming, President Obama today accused House Republicans of extortion, saying a "faction" of lawmakers threatens to force the United States into default unless he agrees to delay or defund his signature health care law.

"You have never seen in the history of the United States the debt ceiling or the threat of not raising the debt ceiling being used to extort a president … and trying to force issues that have nothing to do with the budget and have nothing to do with the debt," Obama said in speech to the Business Roundtable, a nonpartisan association of top American CEOs.

"That a budget is contingent on us eliminating a program that was voted on, passed by both chambers of Congress, ruled constitutional by the Supreme Court, is two weeks from being fully implemented and that helps 30 million people finally get health care coverage; we've never seen that become the issue around a budget battle," he said of the Affordable Care Act.

House Goes All-In to Defund Obamacare

Many House Republicans have sought to use the upcoming fiscal fights to extract concessions from the White House on the health care law, saying they will use any means available as leverage. House Speaker John Boehner said today his chamber would pass a temporary funding measure this week that would keep the government running but also "defund Obamacare."

"The law is a train wreck," Boehner said today. "We're going to continue to do everything we can to repeal the president's failed health care law."

With Boehner and Obama entrenched in opposing positions, the stage is set for another found of fiscal brinkmanship. The government will run out of money Sept. 30 unless Congress can reach a deal on the budget. The United States could reach default in about four weeks in mid-October.

The health care law has been taking effect in stages since 2010. New insurance exchanges take effect Oct. 1, allowing Americans without coverage to purchase subsidized plans in a central marketplace.

Obama said today that is "happy to negotiate with [Republicans] around the budget" but will not negotiate on an increase to the debt ceiling. He opposes any measure to defund the health care law, setting the stage for another impasse between the White House and Capitol Hill.

"What I will not do is to create a habit, a pattern, whereby the full faith and credit of the United States ends up being a bargaining chip to set policy," Obama told the CEOs. "

A Boehner spokesman disputed the president's characterization of the latest fiscal standoff, arguing that Republicans are not threatening default over Obamacare.

"No one is threatening to default," spokesman Brendan Buck said. "The president only uses these scare tactics to avoid having to show the courage needed to deal with our debt crisis. Every major deficit deal in the last 30 years has been tied to a debt-limit increase, and this time should be no different."

But so far there are no apparent attempts even to reach a deal. Negotiations on both issues are non-existent.