White House talks on raising the U.S debt limit, before it expires this week, have been delayed to allow lawmakers more time to hammer out a deal. President Obama was scheduled to meet top Republican and Democratic Party chieftains at the White House yesterday. Democratic and Republican lawmakers are also at loggerheads over a partial government shutdown, which is now in its third week. But congressional leaders say there has been progress in their negotiations to find a way out of the impasse. The IMF says a U.S debt default would trigger global economic turbulence. On Thursday, the U.S must raise its 16.7 trillion dollar borrowing limit so that the nation can pay its bills.