By Tamas Csonka in Budapest Hungary’s ruling Fidesz party has withdrawn its candidate for Budapest mayor, leaving the June 9 election a wide-open contest between incumbent liberal Gergely Karacsony and David Vitezy, a former Fidesz technocrat fielded by the green LMP party. Prime Minister Viktor Orban is taking a gamble with the move in order to topple the high-profile opposition mayor of the capital. The decisions could backfire if Karacsony remains in power. It also sends the message that Fidesz, which has dominated each general election for the last 14 years, is unable to field a potent pol…