On this day in 1990, the Central Committee of the Communist Party of the Soviet Union agreed to give up its monopoly of power based on the recommendation of General Secretary Mikhail Gorbachev.
In the aftermath, fifteen of the constituent republics of the USSR held their first competitive elections. the CPSU lost six of those republics.
According to Wikipedia:
The constituent republics began to declare their national sovereignty and began a “war of laws” with the Moscow central government; they rejected union-wide legislation that conflicted with local laws, asserted control over their local economy and refused to pay taxes. President Landsbergis of Lithuania also exempted Lithuanian men from mandatory service in the Soviet Armed Forces. This conflict caused economic dislocation as supply lines were disrupted, and caused the Soviet economy to decline further.