Former Environment Minister Shinjiro Koizumi is leading in support from fellow parliamentarians in Japan’s ruling party leadership race, polls showed, raising the possibility of him becoming the nation’s youngest prime minister.

The 43-year-old Koizumi gained more than 50 of the 368 votes from legislators in the ruling Liberal Democratic Party, according to surveys by the Sankei and Mainichi newspapers published over the weekend. The leadership election for the conservative party is on Sept. 27 and the winner is almost certain to be elected as prime minister shortly after that due to the LDP’s dominance in parliament.

The race is one of the most wide open in the LDP’s history. The surveys said many legislators remain undecided or could still change their minds, indicating a fluid situation with just a few days to go until the vote, in which rank-and-file members will also cast ballots.