[citation needed] In 1999, he resigned from his position in the Ministry of Finance to run for the House of Representatives in Chiba Prefecture.

Nagata later claimed he had said nothing of the sort and was actually only stating that then Prime Minister Yoshirō Mori was unfit to be the leader of his country.

On April 5, 2001, he asked questions at the main session of the Diet without written notes, opening the doors for a new level of preparedness in younger politicians who do not need to follow scripts in making speeches or during hearings, unlike their older peers.

On February 16, 2006, Nagata accused in parliament former Livedoor CEO Takafumi Horie of bribing the son of Tsutomu Takebe, the Liberal Democratic Party secretary general, through consulting fees.

Democratic Party of Japan (DPJ) secretary general Seiji Maehara called for the government to investigate the matter.