Israel's foreign minister says he will not sit in Prime Minister Benjamin Netanyahu's incoming government and instead will take his Yisrael Beitenu party into the opposition.Monday's announcement by Avigdor Lieberman dealt a setback to Netanyahu, who is trying to cobble together a majority coalition in the 120-seat parliament by a Wednesday deadline. Lieberman has served two terms as foreign minister and has been a key ally of Netanyahu's throughout the years.Lieberman said he could not sit in the government after Netanyahu struck a series of deals with ultra-Orthodox partners. Lieberman's party is secular.Lieberman's once-powerful party plummeted in the March election to just six seats. Without Yisrael Beitenu, Netanyahu is expected to have a slim majority of just 61 seats, leaving him susceptible to the demands of partners.