 Complete the following phrase:  Ukraine was the second-most powerful republic in the Soviet Union both economically and politically behind Russia, and its secession ended any realistic chance of Gorbachev keeping the Soviet Union together. By December 1991 all former Soviet Republics except the RSFSR and the Kazakh SSR had formally seceded from the Union. A week after his election, Kravchuk joined with Yeltsin and Belarusian leader Stanislav Shushkevich in signing the Belavezha Accords, which declared that the Soviet Union had ceased to exist. The Soviet Union 