(ANSA-AFP) - SOFIA, MAY 22 - Former EU commissioner for innovation Mariya Gabriel, tasked with leading political negotiations in Bulgaria, said on Monday that a compromise to form "a stable government" had been reached after five elections in two years. "We all made a lot of concessions," Gabriel told a news conference in the country's capital Sofia. The two biggest parties in the Bulgarian parliament -- Gabriel's conservative GERB and the anti-graft We Continue the Change (PP) -- will propose a government of experts for a period of 18 months. The 44-year-old ex-commissioner, who resigned from her post in Brussels last week, will initially be deputy prime minister, under the leadership of 60-year-old researcher Nikolay Denkov of the PP. Denkov and Gabriel will rotate as prime ministers for a period of nine months each. (ANSA-AFP).