Members of his extended family have largely shunned Robert F. Kennedy Jr.’s presidential campaign, calling it dangerous, and been supportive of President Biden’s reelection. But they made their endorsement official and emphatic on Thursday, Politico reports, appearing with Biden on Thursday in Philadelphia. “We want to make crystal clear our feeling that the best way forward for America is to reelect Joe Biden and Kamala Harris to four more years,” Kerry Kennedy told the gathering. She led a chant of “four more years” and did not mention her brother in her speech. Biden, she said, is “a champi…