Vaccination minister Taro Kono is still the most popular choice among ruling Liberal Democratic Party rank-and-file members to be the next head of the LDP and hence Japan's prime minister, a Kyodo News poll showed Sunday, ahead of the party's presidential election later this week.

After incorporating LDP Diet members' planned votes, however, none of the four candidates in the LDP leadership race is likely to win an overall majority vote in the first round, meaning the successor to Prime Minister Yoshihide Suga is expected to be determined in a runoff vote.

Among the rank-and-file voters, Kono gained 47.4% support, down 1.2 percentage points from the previous survey held earlier this month, and was followed by former Foreign Minister Fumio Kishida at 22.4%, up 3.9 points.