After the Transition, he joined the Abertzale left movement, was a member of the HB National Bureau and in 1979 was a member of Madrid on behalf of the coalition. A year after his death, the book Telesforo Monzon, herri baten oihua was published, which has now been reedited by the Txalaparta and the Olaso Tor Foundation.

It is basically a collection of articles published by the Berber politician since 1976 or several personal interviews to himself, as well as songs and poems he has created himself. Monzón was a charismatic leader on the left Abertzale and his ideas, more than in writing, have spread through songs among all the colors of the left Abertzale: Pantxoa eta Pello sing Aupa gizonak, Lepoan hartu, Itziarren Semea, Plazara or Bai Euskari are some of them sung over decades and can still be heard over many meals. It is worth mentioning the interview carried out in 1979 by the International Press Club in Madrid to many invited journalists, or the interview granted in 1980 to the German magazine Der Spiegel, which would never be published.

The editorial warns that the languages of origin of the publications have been respected and that, therefore, most of the interviews and articles are in Spanish. It has the prologues of HB leader Santi Brouard and the historic leader of the Abertzale left Itziar Aizpurua, killed by the GAL. The latter says in it: “Today, when an opinion of what happened in this battle of the story tries to impose the path of all means and many people remain humble, Monzón’s words and writings have an incredible value in understanding what has happened in our country.”