Should they fail to find a compromise several government agencies will close on Oct. 1, putting hundreds of thousands of non-essential staff on unpaid leave.
Obama is also facing another battle to raise the country’s debt ceiling as the government is expected to run out of cash in the middle of next month, meaning it could default on its repayment obligations.
A similar standoff in 2011 sent global markets slumping and led to the historic downgrade of the US sovereign debt rating.
White House senior advisor Dan Pfeiffer accused Republicans of caring “more about scoring political points on Obamacare than keeping the government open and our economy moving forward.”
On Wall Street Monday the Dow fell 0.32 percent and the S&P 500 lost 0.47 percent. The Nasdaq shed 0.25 percent despite a surge in Apple shares after the computer giant said it sold nine million new iPhones over the three-day launch weekend.