In 1966 Hayes, then residing in Middlebury, ran unsuccessfully for governor, and lost the Republican nomination to Richard A. Snelling. He was the successful Republican nominee for lieutenant governor in 1968 and served one term, 1969 to 1971. Active in opposition to the Vietnam War, he made national headlines in 1970 when, as acting governor, he ordered Vermont flags lowered to half staff after the killing of four students at Kent State University by National Guard troops. In response Governor Deane Davis returned to Vermont from a conference and countermanded Hayes's directive.