Environment Minister Yuriko Koike wrested the Tokyo No. 10 district seat in Sunday’s election from former Liberal Democratic Party member Koki Kobayashi.

The race between Koike and Kobayashi was symbolic of Prime Minister Junichiro Koizumi’s purge of LDP old-guard resistance to reform.

Members of the same party until just last month, when Koizumi dissolved the House of Representatives, the 53-year-old Koike was pitted by the LDP to run against Kobayashi, 61, in his home district.

“I am glad that I fulfilled my role as a candidate to represent voters who support the reforms,” Koike said after learning of the early projections.

“I think the results show that voters want the Koizumi administration to push forward and speed up all kinds of structural reforms, including postal privatization,” Koike said on an NHK program.

A former television anchorwoman, Koike originally held a seat from the proportional representation sector of western Japan’s Kinki block, which includes her electoral base in Hyogo Prefecture.

The victory by Koike, one of more than 30 “assassin candidates” the LDP fielded, will boost Koizumi’s bid to tighten his reform plans centering on postal privatization by seeing those opposing him removed from power.

Koike, a graduate of Cairo University fluent in English and Arabic, urged voters to support the government’s structural reform path, including the speedy privatization of Japan Post.

“Unfortunately, the public believes postal reform is equal to progress in reforming Japan,” Kobayashi told reporters after learning of projections that the ruling coalition was set to secure a majority. “Such a trend makes it difficult for voters to cast their ballots for candidates who think otherwise.”

Kobayashi was among 37 LDP Lower House members who voted against the postal privatization bills in July. He split ranks with the party and ran on the ticket of the newly launched New Party Nippon.

In stark contrast to Koike, Kobayashi said during the campaign that privatizing Japan’s postal services and postal savings must be done gradually and criticized Koizumi for clamping down on dissenting opinion within the LDP.

Despite being parachuted in by the LDP to run in Kobayashi’s home turf and having limited time to campaign, Koike successfully secured support from 46.1 percent of nonaligned voters, according to Kyodo News exit polls.

She won votes from supporters of both the governing and opposition parties — 75.1 percent of the LDP supporters, 93.6 percent of New Komeito supporters and 19.3 percent of the Democratic Party of Japan supporters polled.

Of the female “assassins” handpicked by Koizumi, Koike captured the votes of 55.8 percent of the women voters polled.

Kobayashi received votes from only 15.1 percent of LDP supporters, 19.3 percent of DPJ supporters and 18.4 percent of nonaligned voters, according to the exit polls.