WASHINGTON (AP) — After weeks of stubborn gridlock, the Senate's top two leaders raced on Monday to reach an agreement that could head off a Treasury default that threatens severe national economic damage and reopen the government after a two-week partial shutdown.

As a midweek deadline neared, the stock market turned positive on bullish predictions from the two longtime antagonists at the center of the talks, Majority Leader Harry Reid for the Democrats Republican leader Mitch McConnell for the GOP.

Under the terms they were discussing, the $16.7 trillion federal debt limit would be raised enough to permit the Treasury to borrow normally until mid-February if not several months longer. The government would reopen with funds sufficient to operate until mid-January at levels set previously. The government has been partly closed since Oct. 1, and the administration says the Treasury will run out of borrowing authority to fully pay the nation's bills on Thursday.