By ZEKE MILLER, WILL WEISSERT and CHRIS MEGERIAN / AP April 18, 2024 8:58 AM EDT WASHINGTON (AP) — President Joe Biden will accept endorsements from at least 15 members of the Kennedy political family during a campaign stop in Philadelphia on Thursday as he aims to undermine former President Donald Trump and marginalize the candidacy of Robert F. Kennedy Jr. Kerry Kennedy, a daughter of former Attorney General Robert F. Kennedy, niece of former President John F. Kennedy and sister of the