In the years before World War I, he joined the young generation of Christian Socialist activists around the Carniolan priest Janez Evangelist Krek, who challenged the conservative leadership of the Slovene People's Party.
Between 1913 and 1914, he was the president of the Christian Social Association (Krščansko-socialna zveza) in Gorizia and Gradisca, and between 1917 and 1919 he was a personal secretary of the chairman of the Slovene People's Party, Anton Korošec.
After World War One, he returned to Gorizia, and soon became one of the main figures of Slovene and Croat political Catholicism in the Julian March, an administrative region formed out of the former Austro-Hungarian Adriatic provinces annexed to Italy.
Besednjak thus became, together with the national liberal politician Josip Wilfan who was also elected on the same list, the highest representative of the around half a million South Slavs living in Italy.
In 1929, Besednjak emigrated to Argentina, but already the following year he returned to Europe in order to work at the Congress of European National Minorities in Vienna, serving as its vice-president.
Throughout the interwar period, he remained a member of the Slovene People's Party, supporting its centrist faction led by the Christian Democratic politician Andrej Gosar.
After 1943, he collaborated with the so-called "Catholic Centre", led by Jakob Šolar and Andrej Gosar in the Province of Ljubljana, and Virgil Šček in the Julian March, trying to keep a balance between the pro-Communist Liberation Front of the Slovenian People and various anti-Communist forces.
[2] After 1944, however, he became increasingly supportive of Josip Broz Tito's partisan movement, believing that the Communists would be the only force able to achieve the annexation of the Slovenian Littoral and Istria to Yugoslavia, as well as the only ones capable to keep the country together.