Just a day after the surprise announcement of her candidacy in a Lower House by-election, the widow of lawmaker Shokei Arai decided Thursday to pull out of the running to fill the seat made vacant when her husband hanged himself last week.

A secretary to Mariko Arai, 45, on Thursday morning told a faction within the Liberal Democratic Party, to which the late Arai belonged, that his widow had withdrawn her candidacy in the March 29 election. On Wednesday, she had told a news conference that she wanted to run in the election to prove her husband was innocent of allegations that he demanded illegal profits from Nikko Securities Co.

The lawmaker hanged himself on Feb. 19 at a Tokyo hotel just hours before he was to be arrested by prosecutors. He had belonged to an LDP group led by former Finance Minister Hiroshi Mitsuzuka. According to members of the faction, Arai explained that she has withdrawn from the race because her son and others had urged her to drop the idea for health reasons.

At a news conference held the day after her husband's funeral, Arai said she had "reached the conclusion that this is the only way to prove my husband's innocence and vent his anger." Arai said she would consider seeking the LDP's backing in the by-election, but added that she would run as an independent if she could not get the support of the ruling party.

The LDP was apparently caught off balance by her decision to run, and her chances of winning were said to be slim. Meanwhile, party sources said it would have been difficult for the LDP to field a contender if Arai did not run on the LDP's ticket.

Lower House member Takashi Fukaya, who heads the LDP's Tokyo chapter, ruled out the possibility of Arai running on the party's ticket. While some members of the Mitsuzuka faction initially said they would support her, senior leaders of the group agreed later it would be difficult to extend such help.

Former Lower House member Tetsu Ueda, 70, declared Wednesday his candidacy for the by-election to fill the vacancy in the Tokyo No. 4 district. The LDP is said to be looking for a candidate to support, and has narrowed its list down to Keigo Ouchi, former chairman of the now-defunct Democratic Socialist Party, Kensaku Morita, a former actor and current LDP member of the Upper House, and Yoshio Nishino, head of Tokyo's Ota Ward, party sources said.