WASHINGTON (AP) — President Joe Biden at his first news conference Thursday left the door open to backing fundamental changes in Senate procedure to muscle key parts of his agenda like immigration and voting rights past Republican opposition “if there’s complete lockdown and chaos.”

Even as his administration navigates the COVID-19 pandemic and the resulting economic damage, Biden is grappling with how to deliver on a host of big promises despite a razor-thin Senate majority. He teased that changes to Senate rules that would allow bills to pass with fewer votes may be necessary for him to achi...