Complex sentence: In an attempt to succeed his father, he ran as Democratic candidate for New York Governor in 2002, but withdrew before the primary after criticizing Republican incumbent George Pataki's leadership following the terrorist attacks on the city on September 11 the previous year.
Split into simpler sentences: In an attempt to succeed his father, he ran as Democratic candidate for New York Governor in 2002, but withdrew before the primary. He withdrew after criticizing Republican incumbent George Pataki's leadership following the terrorist attacks on the city on September 11 the previous year.