Ivan Boky said, "The president ruined the coalition by nominating Petro Poroshenko for the post of [Supreme Rada] speaker."
The coalition of Western-leaning forces broke up when the Party of Regions, holding 186 seats in the Rada, and the Socialist and Communist parties with 33 and 21 seats respectively joined forces late Thursday to elect Socialist leader Oleksandr Moroz as speaker.
The three parties are currently holding talks on the formation of a new parliamentary coalition.
Boky said anarchy followed the collapse of the "orange" coalition that "ruined the economy and created political instability."
"Therefore, we had to assume responsibility and search for a way out of this situation," he added.
The Socialists were accused of breaching an agreement with its "orange" allies, pro-presidential Our Ukraine grouping and the bloc led by Yulia Tymoshenko, who was Ukraine's prime minister for eight months last year and is aspiring to the post again. The "orange" coalition, made up of the three parties that propelled Viktor Yushchenko to the presidency in the "orange revolution" of 2004, earlier planned Poroshenko, an Our Ukraine candidate, as Rada speaker.
Tymoshenko said earlier Friday that the "orange" coalition had ceased to exist and urged President Viktor Yushchenko to either approve a new coalition or dissolve the Rada.
The Rada, meanwhile, is to form the government by July 22. After this deadline the president is entitled to dissolve legislature and call new elections.