TOKYO (Reuters) - A newly elected member of Japan‘s Upper House of parliament has declared affiliation with the ruling Liberal Democratic Party, increasing the number of voters in an LDP presidential election on Friday to 414, a party official said on Thursday. The new LDP president is almost certain to become Japan‘s next prime minister due to the party‘s majority in the Lower House of parliament. An official at the LDP secretary-general‘s office said Naoki Tanaka, who stood as an independent in an Upper House election on July 12, had declared affiliation with the LDP and would vote in the presidential contest. LDP members of parliament and a party representative from each of Japan‘s 47 prefectures will vote to choose a successor to Prime Minister Ryutaro Hashimoto, who is resigning over the party‘s drubbing in the July 12 Upper House election. Seiroku Kajiyama, a former chief cabinet secretary, Health Minister Junichiro Koizumi and Foreign Minister Keizo Obuchi are competing for the post. If no candidate receives 208 or more votes in the first round, the two with most votes will go into a runoff.