Between 1967 and 1971 Callejas worked at the Council for Economic Planning (CONSUPLANE). In 1968, Callejas was made the Director of Economic Planning by the then President Oswaldo López. in 1975 another General and President, Juan Alberto Melgar, named Callejas Minister for Agriculture and Natural Resources. When another general and President Policarpo Paz took over in a coup in 1978, Callejas remained in his post. During the transition to democracy culminating in November 1981 elections, which were won by the Liberal Party of Honduras (PLH), he rose within the ranks of the National Party of Honduras (PNH), and in 1982 presided over their central committee. He supported former President Ricardo Maduro's Unidad y Cambio (Unity and Change) movement within the PNH that brought the party more towards the center, and a liberal economic path. Callejas then created his own faction, the Movimiento Nacional Callejista (National Callejista Movement), to advance his candidature in the 1985 presidential elections. At the time both main political parties allowed various candidates to stand, and while Callejas gained the highest vote of any candidate with 42.6%, the PLH candidates gained 51.5% of the total vote, and therefore it was their most voted for candidate, José Azcona, with 27.5% of the vote, who became President.