Former Defense Minister Yuriko Koike is gaining the upper hand in the race for Tokyo governor, followed by former internal affairs minister Hiroya Masuda and veteran journalist Shuntaro Torigoe, a Kyodo News survey has shown.

Still, the potential for a tight race remains high ahead of next Sunday’s election, with 31.1 percent of respondents saying they had yet to decide who to vote for, the telephone survey conducted Saturday and Sunday showed.

Koike has the support of nearly 35 percent of unaffiliated voters and some ruling Liberal Democratic Party backers, although the 64-year-old former Lower House member is running without the party’s blessing.