Complex sentence: He boasted of being friends with Bill and Hillary Clinton, and Barack Obama; the Clintons continued longstanding close relationships with the producer despite alleged warnings to the Hillary Clinton presidential campaign about Weinstein from Lena Dunham and Tina Brown.
Split into simpler sentences: He boasted of being friends with Bill and Hillary Clinton, and Barack Obama. The Clintons continued longstanding close relationships with him despite alleged warnings about Weinstein to Hillary Clinton's presidential campaign from Lena Dunham and Tina Brown.