At the 1952 Republican National Convention he played a key role in winning the GOP presidential nomination for General Dwight Eisenhower.

As postmaster general, Summerfield oversaw attempts to reform and modernize the Post Office and the U.S. mail system, which was still conducting many sorting and processing operations by hand.

Summerfield called for an increase in postage rates to subsidize the purchase of new mechanized mail processing and sorting equipment.

In 1955, postal inspectors seized a rare volume of the 2,400-year-old play Lysistrata by Aristophanes, which Summerfield described as "obscene, lewd and lascivious".

[1] When the first unexpurgated edition of Lady Chatterley's Lover was published in the US in 1959 by Grove Press, Summerfield moved to ban it from being sent by mail, saying that "any literary merit the book may have is far outweighed by the pornographic and smutty passages and words".

In January 1961, toward the end of his tenure as Postmaster General, Summerfield oversaw the indictment in Chicago of more than fifty members of the "Adonis Male Club", a gay pen pal service, for conspiracy to send obscene materials through the mail.