Senior White House adviser Dan Pfeiffer on Thursday likened Republican lawmakers to suicide bombers amid a high-stakes showdown between the GOP and President Obama which could lead to a possible government shutdown or default.

"We are for cutting spending, we are for reforming our tax code, we are for reforming entitlements. But what we are not for is negotiating with people who have a bomb strapped to their chest," said Pfeiffer on CNN's "The Lead with Jake Tapper."

"So if they want to have a discussion about how we reduce our deficits and how we help the middle class, how we give them a better bargain, lift the debt ceiling. Take the full faith and credit of the United States off the table and lets have a discussion," he added.

Pfeiffer's comments come as the GOP-controlled House and Democratic Senate remain at loggerheads over a spending bill to fund the government and avert a shutdown Oct. 1.

Conservatives want to use the continuing resolution to defund Obamacare and a measure to raise the nation's debt ceiling by mid-October to push for further spending cuts and entitlement reforms.

The House-passed continuing resolution funds the government but strips money for Obamacare. The Senate is likely to pass a measure later this week without defunding the president's signature healthcare reform law.

House Speaker John Boehner, R-Ohio, on Thursday also unveiled a list of demands in exchange for raising the nation's borrowing limit. Boehner added that he thought a vote on the "clean" Senate continuing resolution was unlikely in the House, raising the prospect of a shutdown.

President Obama has said he will not sign any bill that defunds healthcare reform and will not negotiate with Republicans over the debt limit.

In a speech earlier Thursday Obama accused Republicans of trying to "blackmail" him.

“The Tea Party Republicans have taken it to a whole new level because they're threatening to shut down the government or shut down the entire economy unless I agree to gut a law that will help millions of people,” Obama said.