Complex sentence: Running mate Joe Lieberman later criticized Gore for adopting a populist theme during their 2000 campaign, and stated he had objected to Gore's "people vs. the powerful" message, believing it was not the best strategy for Democrats to use to win the election.
Split into simpler sentences: Running mate Joe Lieberman later criticized Gore for adopting a populist theme during their 2000 campaign. He stated that he had objected to Gore's "people vs. the powerful" message, believing it was not the best strategy for Democrats to use to win the election.