HARRISBURG, Pa. (AP) — President Joe Biden urged his supporters to stay unified during a series of Sunday stops in critical Pennsylvania on Sunday, even as some leading congressional Democrats privately suggested it was time for him to abandon his reelection bid because of intensifying questions about whether he’s fit for another term. Addressing a rousing church service in front of stained glass windows bathed in sunshine at Philadelphia’s Mount Airy Church of God in Christ, the 81-year-old Biden joked, “I know I look 40” but “I’ve been doing this a long time.” “I, honest to God, have never b…