Clime first became involved in nationalist political organizing in his school days, first as a member of the nationalist group "Avântul", where he became acquainted with philosopher Nae Ionescu.
He later became acquainted with A. C. Cuza, the founder of the National-Christian Defense League, an antisemitic and ultranationalist political party created in 1923. Clime was named Vice-President of the National-Christian Defense League for the region of Moldova for a short period of time.[1]
By 1926, following a split in the League, Clime left and forged a closer relationship with fellow ex-member Corneliu Zelea Codreanu. In July 1927, Codreanu announced the foundation the Legion of the Archangel Michael (or Legionary Movement), a new militant fascist, Orthodox, and ultranationalist group. Clime soon began collaborating on Pământul strămoșesc, an early Legionary periodical published beginning in August 1927. On 8 November 1927, Clime, alongside other founding members of the movement (including Codreanu, Ion Moța, Ilie Gârneață, Corneliu Georgescu, and Radu Mironovici, among others) took an oath as members of the Legionary Movement.
During the 1932 Romanian general election, Clime ran as a candidate under the Legion's electoral name "Garda de fier" ("Iron Guard") in Domnești.[2] The party earned 5 seats in the Chamber of Deputies, with 70,674 votes (around 2.44% total).[3]
Following the assassination of Prime Minister Ion G. Duca in 1933 by an Iron Guard death squad, Clime was caught carrying Legionary publications and arrested together with other close associates of the Legionary Movement.[4][5] Imprisoned briefly at Jilava Prison, he was acquitted of all charges in April 1934. That year, he and his family relocated to Bucharest, where he was promoted to General Secretary of the Legionary Movement. In December 1936, Codreanu established the rank of "Commander of the Annunciation" (in Romanian, "Comandant al Bunei Vestiri") within the Legionary Movement, denoting the highest level in the Legion's hierarchy, and Clime was promoted to this rank alongside other founding members Ion Moța, Corneliu Georgescu, Ilie Gârneață, Radu Mironovici, Mille Lefter, and Ion Blănaru.[6]
In 1936, Clime was put in charge of the newly-founded Corpul Muncitoresc Legionar ("Legionary Workers' Corps"), a workers' faction of the movement.[7] Later that year, following the outbreak of the Spanish Civil War, the Legionary Movement organized a team of volunteers to fight against the Republicans, on the side of the Nationalists. Led by Gheorghe (Zizi) Cantacuzino, the team of volunteers consisted of Clime, Ion Moța, Vasile Marin, Alexandru Cantacuzino, Bănică Dobre, Ion Dumitrescu-Borşa, and Niculae Totu.[8] After the deaths of Moța and Marin (see: Funerals of Ion Moța and Vasile Marin) the team returned to Romania.
After the death of Gheorghe Cantacuzino in 1937, Clime succeeded him as President of Totul pentru Țară ("Everything for the Country"), the Legionary Movement's electoral party.[7] In the same year's general election, the party earned 66 seats in the Chamber of Deputies, with around 15.81% of the total vote.[3]