Factbox: Main parties in Bulgaria's election

(Reuters) - Millions of Bulgarians will cast their ballot in a snap election on Sunday, a vote that could produce another shaky coalition struggling to solve a festering bank crisis and revive growth in the European Union's poorest member state. Led by a former bodyguard and karate expert, the center right GERB party is expected to win but fall short of a majority, which could spark a period of haggling with smaller parties and the opposition to shore up support. Following is a list of Bulgaria's main parties. GERB The center-right party was in power until February 2013, when it collapsed amid mass protests over high electricity bills and low living standards. Led by Boiko Borisov, a former prime minister and one time professional bodyguard, the party will propose legal changes to safeguard the independence of the energy regulator. That would ensure that prices would not be kept artificially low due to political pressure. Instead, GERB plans to offer energy aid to the poorest and overhaul aging communist-era apartment blocks, home to some 700,000 households, to cut energy consumption. It has vowed not to continue with the controversial, Russian-led South Stream pipeline unless given the green light from Brussels. It aims to push ahead with a bid to join the European Union's banking union, keep the corporate tax rate at 10 percent and strengthen Bulgaria's positions in the EU and NATO. SOCIALISTS The Socialists' coalition government was forced to resign in July after barely a year in office, following its woeful performance at the European Parliament elections. It will likely be the second-biggest party after the vote. A previous Socialist government oversaw a period of boom and then bust in 2005-2009. The party is descended from Bulgaria's former communist rulers. Many of its supporters favor closer ties with Russia, support Russia energy projects such as the South Stream gas pipeline and oppose new sanctions against Moscow. The party wants to scrap Bulgaria's flat income tax rate in favor of progressive taxation to ease the burden on the poor. MOVEMENT FOR RIGHTS AND FREEDOMS The liberal MRF party, a junior coalition partner in the previous Socialist-led government, represents ethnic Turks and other Muslims, who make up about 12 percent of the Balkan country's 7.3 million people. The party may provide outside support for a GERB government after a serious rift opened up with the Socialists this year. The MRF is pro-Europe, wants more subsidies doled out to smaller farmers and to speed up development in rural Bulgaria. REFORMIST BLOC A coalition of five right-wing and centrist parties that was set up in the wake of massive anti-corruption protests last year. It is seen as GERB's most likely coalition partner. It has promised a war on corruption, transparent public procurement deals, an overhaul of Bulgaria's slow-moving judicial system and to keep tax rates unchanged. BULGARIA WITHOUT CENSORSHIP A centrist, populist coalition led by former TV anchor Nikolay Barekov, that seeks to become the new kingmaker in parliament. It promised to create 1 million jobs in eight years, increase teachers' pay and the lowest pensions by 20 percent, and provide free medicines for pensioners. ATTACK A nationalist party that is against Bulgaria's membership in NATO, questions its place in the European Union, and favors closer ties with Russia. It silently propped up Bulgaria's Socialist-led coalition government in parliament and its popularity has dwindled as a result. Its colorful leader was charged with hooliganism for his alleged involvement in an airport scuffle in January. PATRIOTIC FRONT The coalition, led by two nationalist factions, NFSB and VMRO, is seen as less extreme than the Attack party, and a more acceptable ally for a GERB-led government. The nationalists demand urgent measures to deal with Bulgaria's aging and rapidly shrinking population. They also want to ban parties formed on ethnic lines and limit social handouts that often go to Bulgaria's Roma minority. (Reporting by Angel Krasimirov and Tsvetelia Tsolova; editing by Matthias Williams)