Polling stations opened Sunday morning throughout Japan for tens of millions of voters who will elect 121 upper house lawmakers, dpa reported. All eyes are on Prime Minister Shinzo Abe's ruling Liberal Democratic Party (LDP), its coalition partner Komeito and like-minded parties and whether they will gain a two-thirds majority in the House of Councillors. Abe would need the support of two-thirds of both chambers of parliament in order to call a national referendum on amending the constitution. The ruling coalition already holds a majority in the House of Representatives, the more powerful lower house. The ruling coalition is likely to surpass the premier's target of 61 of the 121 seats in the upper chamber up for grabs in the race, major polls showed, despite Abe's government's failure to revitalize long-term economic growth. The main opposition Democratic Party is expected to win 30 seats, far below its 43 contested seats, according to a recent survey conducted by the major daily newspaper Asahi. Every three years Japan's upper house holds elections for half of its 242 seats. This year a total of 389 candidates are running for the 121 seats. Of the 106.6 million registered voters in Japan, about 13.2 million people cast their ballot in early polls until Friday, according to the Ministry of Internal Affairs and Communications. The polls opened at 7 am local time (2200 GMT Saturday) and will close at 8 pm.