WASHINGTON (AP) — Seventy-seven-year-old Joe Biden says he would like to be a “transition” from President Donald Trump to younger, rising Democratic figures. Biden is the presumptive Democratic presidential nominee, and his choice of a running mate could be seen as a possible president-in-waiting who’s able to lead the party beginning in 2024. But no president since Reconstruction has passed up seeking reelection after just four years in office. And the Democratic Party may not fall peacefully in line behind Biden’s chosen successor. The question of his long-term prospects looms over his candidacy, especially as he considers his options for vice president.