Anatoliy Kinakh, head of the National Security and Defense Council, said that he wanted to focus on work in parliament to help make it "coordinated, pragmatic, efficient and professional."
Kinakh had been elected to parliament as a candidate in President Viktor Yushchenko's bloc. His resignation came a day after the head of Ukraine's state-owned oil and gas company, Oleksiy Ivchenko, made a similar departure.
Both men have a history of tense relations with former Prime Minister Yulia Tymoshenko, and their resignations could be a signal that perhaps the closed door coalition talks were shifting in favor of Tymoshenko, who has been lobbying to regain the premier's job, the AP reports.
The talks to get a new government in place have dragged on since the March 26 elections, in which no party won a majority. The Party of Regions, led by Yushchenko's Orange Revolution foe Viktor Yanukovych, was the single largest vote-getter. But the estranged parties that led the 2004 Orange Revolution - Yushchenko's and Tymoshenko's blocs and the Socialists - have been struggling to overcome their differences and reunite to keep Ukraine on its pro-Western path.
After it turned out that Deputy Prime Minister Andrei Belousov included the Fonbet betting company in the list of backbone enterprises that can count on state support, everyone started talking about these bookmakers.