WASHINGTON (AP) — Year-end pileups of crucial legislation and the brinkmanship that goes with it are normal behavior for Congress. This time, lawmakers are barreling toward an autumn of battles striking for the risks they pose to both parties and to their leaders. Democrats aren’t sure they’ll have the votes to enact President Joe Biden’s top priorities into law. Republicans worry that Democrats may weaken the filibuster rule that lets the Senate’s minority party derail legislation. And no one seems certain how Congress will extend the government’s authority to borrow money. Miscalculate and there could be a federal default, a collapse of Biden’s domestic agenda and a government shutdown.