Complex sentence: Gorbachev regarded the Communist Party and Yeltsin as being the two forces that thrust him out of power, and encouraged his supporters to abstain from voting in a second round if it were to be between those two candidates.
Split into simpler sentences: Gorbachev regarded the Communist Party and Yeltsin as being the two forces that thrust him out of power. Gorbachev encouraged his supporters to abstain from voting in a second round if it were to be between those two candidates.