Former Chief Cabinet Secretary Yasuo Fukuda has narrowed the gap with Shinzo Abe, the current chief Cabinet secretary, in a popularity ranking of possible candidates to replace Prime Minister Junichiro Koizumi, an opinion poll showed Monday.

Fukuda scored 31.4 percent, up from 22.1 percent in April, while Abe's support fell to 40.1 percent, down from 51.9 percent, according to results of the telephone poll conducted Saturday and Sunday.

Asked if the next prime minister should visit Yasukuni Shrine, a slender majority of 51.8 percent said no, compared with 35.8 percent who said yes.

Fukuda has been critical of Koizumi's visits to Yasukuni and has said he is willing to work to improve Japan's relations with the rest of Asia, which have been marred by Koizumi's shrine visits. Abe has supported the visits.

Foreign Minister Taro Aso and Finance Minister Sadakazu Tanigaki, who are both expected to join the race for the top spot, had support rates of 4.5 percent and 2.7 percent respectively.

The Liberal Democratic Party is scheduled to hold an election in September for its party president. The top LDP official will become prime minister.

The LDP leader is elected by LDP lawmakers and rank-and-file party members.

On domestic reforms, respondents were split over Koizumi's achievements. Some 30.1 percent said the next prime minister should continue Koizumi's structural reforms of the economy, 30.6 percent said Koizumi's policies "should be modified," and 32.3 percent answered they should be "fundamentally revised."

By party, support for the Democratic Party of Japan, the largest opposition party, increased to 24.2 percent from 19.9 percent in April.