The late 1980s and early 1990s saw the collapse of most of those socialist states that had professed a Marxist–Leninist ideology. In the late 1970s and early 1980s, the emergence of the New Right and neoliberal capitalism as the dominant ideological trends in Western politics—championed by American President Ronald Reagan and British prime minister Margaret Thatcher—led the west to take a more aggressive stand towards the Soviet Union and its Leninist allies. Meanwhile, the reformist Mikhael Gorbachev became General Secretary of the Communist Party of the Soviet Union in March 1985 and sought to abandon Leninist models of development towards social democracy. Ultimately, Gorbachev's reforms, coupled with rising levels of popular ethnic nationalism in the Soviet Union, led to the state's dissolution in late 1991 into a series of constituent nations, all of which abandoned Marxist–Leninist models for socialism, with most converting to capitalist economies.