Final answer:
Boris Yeltsin became the president of Russia by winning the country's first open election in 1991. He gained popularity and power for supporting democratic reforms, thwarting an anti-reform coup and playing a significant role in the dissolution of the Soviet Union.
Step-by-step explanation:
Boris Yeltsin became the president of Russia by winning the country's first open election. After the attempted coup in August 1991 by hard-liners in the Kremlin, Yeltsin, who was the president of the Russian republic, acted decisively in support of the reforms and against the coup, which led to his rise in popularity and authority. The subsequent dissolution of the Soviet Union in December 1991, where Yeltsin played a key role, paved the way for his leadership. He did not overthrow Gorbachev in a coup détat; he was not appointed by the Communist Party; nor was he a military leader who took control.
As a popular politician, Yeltsin was instrumental in thwarting the hard-line Communist coup that sought to reverse the democratic revolutions in Eastern Europe. He supported Mikhail Gorbachev's return to office, but he also realized the increasing support for the dissolution of the Soviet Union and independence of its republics. In a historic shift, the republics led by Yeltsin moved towards creating a new political landscape. When the USSR was dissolved, Yeltsin became the leader of the Russian Federation, which emerged from the largest Soviet state.