His parents, Thomas and Frances Montoya, were Roman Catholic descendants of eighteenth-century Spanish settlers to New Mexico.

In 1936 at age 21, while Montoya was still at Georgetown, he became the youngest person in the history of the state to be elected to the New Mexico House of Representatives.

From 1947 to 1957 he was elected Lieutenant Governor of New Mexico three times[2] and also served two additional terms in the State Senate.

Montoya won the 1964 Senate election to complete the term of Dennis Chavez, who died in office.

Montoya won even though the Governor of New Mexico, Edwin L. Mechem, had resigned the governorship in order to fill the seat temporarily.