WASHINGTON (AP) — Former President Joe Biden is returning to the national stage to help elevate concerns that President Donald Trump’s agenda is threatening the health of Social Security. The 82-year-old Democrat has largely avoided speaking publicly since leaving the White House in January. That’s even as Trump frequently blames Biden for many of the nation’s problems. On Tuesday, Biden is expected to fight back in a speech to the national conference of Advocates, Counselors and Representatives for the Disabled in Chicago. The former president has made a handful of public appearances since leaving office, but this marks his highest-profile speech and focuses on a core issue for the Democratic Party.