Dissolution of the Soviet Union:

In the first session of the new Congress of People's Deputies, from May 25 to June 9, hardliners retained control but reformers used the legislature as a platform for debate and criticism which was broadcast live and uncensored. This transfixed the population; nothing like this freewheeling debate had ever been witnessed in the U.S.S.R. On May 29, Yeltsin managed to secure a seat on the Supreme Soviet, and in the summer he formed the first opposition, the Inter-Regional Deputies Group, composed of Russian nationalists and liberals. Composing the final legislative group in the Soviet Union, those elected in 1989 played a vital part in reforms and the eventual breakup of the Soviet Union during the next two years.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". Who used the legislative session to debate and criticize?
reformers