In October 2015, several significant political activities involving major U.S. Democrats took place. Below is a concise summary of these events based on available information:
October 13: The first Democratic primary debate for the 2016 presidential election was held in Las Vegas, Nevada, broadcast on CNN. Candidates included Hillary Clinton, Bernie Sanders, Martin O'Malley, Jim Webb, and Lincoln Chafee, marking a key moment in the Democratic nomination race.
October 20: Former Virginia Senator Jim Webb announced his withdrawal from the Democratic presidential race, citing differences with the party's direction.
October 21: Vice President Joe Biden declared he would not run for president in 2016, ending speculation about his candidacy after months of consideration following the death of his son, Beau Biden.
October 22: Hillary Clinton testified before the House Select Committee on Benghazi for over eight hours, addressing questions about the 2012 Benghazi attack. This high-profile hearing was a focal point for Democratic and Republican political discourse.
October 23: Former Rhode Island Governor Lincoln Chafee dropped out of the Democratic presidential race, further narrowing the field of candidates.
These events reflect the major political activities of prominent Democrats in October 2015, centered primarily on the early stages of the 2016 presidential primary campaign.

