Antonino represented the first district of La Union in the House of Representatives from 1965 to 1969. When her senator-husband Gaudencio died in a helicopter crash while on the campaign trail, she ran for senator as an independent and won. Mrs. Magnolia Welborn-Antonino, wife of the late Senator Gaudencio Antonino was born in Balaoan, La Union. Magnolia was division home economics supervisor of the Bureau of Public Schools when she met Gaudencio Antonino who was then connected with Sta. Clara Lumber Co. Inc. To their marriage were born five sons now living - Victor, Arthur, Adelbert, Gaudencio Jr. and Rodolfo. In 1948 together with her husband, they organized the Western Mindanao Lumber Co. Inc. The logs and lumber boom encouraged the husband-wife team to establish the Mindanao Lumber Development Co. Inc., in 1951, and two years later, the G.E. Antonino, Inc., In 1968 she continued the campaign of her husband who died in a helicopter crash campaigning for senatorial re-election. She won the senatorial chair that year.