Robinson was the Democratic candidate for vice president in 1928, as the running mate of Alfred E. Smith. Early in 1928, Robinson clashed with Senator James Thomas Heflin, a Democrat from Alabama, who frequently inserted anti-Catholic sentiments into many of his speeches. When New York's Catholic governor, Alfred E. Smith, announced his candidacy for president, Heflin made Smith the target of his criticism. Robinson admonished his views, stating that religious affiliation had no bearing on a person's credentials for higher office. On one famous occasion, he declared, "I have heard senator denounce the Catholic Church and the Pope of Rome and the cardinal and the bishop and the priest and the nun until I am sick and tired of it, as a Democrat." Helfin retorted, "The Senator from Arkansas can not remain leader of the Democrats and fight the Roman Catholics' battle every time the issue is raised in this body." Interpreting the remark as a challenge to his authority, Robinson held a vote of confidence to gauge his colleagues' loyalty. By a near unanimous vote (Heflin was absent), the senators pledged their support to their leader and his stance against bigotry.