WASHINGTON — Senate leaders are closing in on an agreement to reopen the government and forestall an economy-rattling default on U.S. obligations. Majority Leader Harry Reid, D-Nev., and GOP leader Mitch McConnell of Kentucky could seal an agreement on Tuesday, just two days before the Treasury Department says it will run out of borrowing capacity. The emerging pact would reopen the government through Jan. 15 and permit the Treasury to borrow normally until early to mid-February, easing dual crises that have sapped confidence in the economy and taken a sledgehammer to the GOP's poll numbers.