After static summer, Democratic race enters a chaotic fall

In this Oct. 10, 2019, photo, Democratic presidential candidate former Vice President Joe Biden speaks during the Power of our Pride Town Hall in Los Angeles. (AP Photo/Marcio Jose Sanchez)

Democratic presidential candidates Sen. Elizabeth Warren, D-Mass., and former Vice President Joe Biden speak during the Power of our Pride Town Hall in Los Angeles on Thursday. (AP Photo/Marcio Jose Sanchez)

WASHINGTON — A Democratic presidential race that had been largely static through the summer has tumbled into a chaotic fall, shaped by unpredictable events and the deepening impeachment crisis surrounding President Donald Trump.