As Congress begins debate this week on sweeping voting and ethics legislation, Democrats and Republicans can agree on one thing: If signed into law, it would usher in the biggest overhaul of US elections law in at least a generation. House Resolution 1, Democrats’ 791-page bill, would touch virtually every aspect of the electoral process — striking down hurdles to voting erected in the name of election security, curbing partisan gerrymandering and curtailing the influence of big money.