WILMINGTON, Del. (AP) — Joseph Robinette Biden Jr. has navigated a half-century in American politics by relentlessly positioning himself at the core of the Democratic Party. Wherever that power center shifted, there Biden has been, whether as the young senator who opposed court-ordered busing in school integration cases or the soon-to-be 46th president pitching an agenda on par with Franklin D. Roosevelt’s New Deal and Lyndon B. Johnson’s Great...