Answer by taking a quote from the following article:

Meir David HaKohen Kahane (; Hebrew: myr dvd khn; August 1, 1932 - November 5, 1990) was an American-Israeli ordained Orthodox rabbi, writer, and ultra-nationalist politician who served one term in the Israeli Knesset. His work is influential on most modern Jewish militant and far right-wing political groups. Kahane spent years reaching out to Jews through published works, weekly articles, speeches, and debates on college campuses and in synagogues throughout the United States, and appearances on various televised programs and radio shows.

In the 1984 legislative elections, Kahane's Kach party received 25,907 votes, enough to give the party one seat in the Knesset, which was taken by Kahane. Kahane refused to take the standard oath of office, and insisted on adding a Biblical verse from Psalms, to indicate that when national laws and the Torah conflict, the Torah (Biblical) law should have supremacy over the laws of the Knesset. Kahane's legislative proposals focused on Jewish education, an open economy, transferring the Arab population out from the Land of Israel, revoking Israeli citizenship from non-Jews, and banning Jewish-Gentile marriages and sexual relations, based on the Code of Jewish Law compiled by Maimonides in the Mishneh Torah.  As his political career progressed, and his popularity in the streets began growing, Kahane became increasingly isolated in the Knesset. His speeches, boycotted by nearly all Knesset members, were often made to an empty parliament, except for the duty chairman and the transcriptionist. Kahane's legislative proposals and motions of no-confidence against the government were ignored or rejected by fellow Knesset members. Kahane often pejoratively called other Knesset members "Hellenists" (a reference to Jews who assimilated into Greek culture after Judea's occupation by Alexander the Great). In 1987, Kahane opened a yeshiva ("HaRaayon HaYehudi") with funding from US supporters, to teach "the Authentic Jewish Idea". Despite the boycott, Kahane's popularity grew among the Israeli public, especially among working-class Sephardi Jews. Polls showed that Kach would have likely received anywhere from four to twelve seats in the coming November 1988 elections.  In 1985, the Knesset passed an amendment to Israel's Basic Law, barring "racist" candidates from election. The Central Elections Committee banned Kahane a second time, and he appealed to the Israeli Supreme Court. This time, the Supreme Court ruled in favor of the committee, disqualifying Kach from running in the 1988 elections. Kahane was thus the first candidate in Israel to be barred from election for racism. The move was criticized as being anti-democratic by Alan M. Dershowitz.

When was he elected?
In the 1984 legislative elections, Kahane's Kach party received 25,907 votes, enough to give the party one seat in the Knesset, which was taken by Kahane.