Kean attended the 1912 Republican National Convention, where he was escorted by his uncle's secretary, Donald H. McLean, with whom he would late serve in Congress.

Young Kean was a Roosevelt supporter, although his uncle and father had publicly endorsed the incumbent President, William Howard Taft.

He served in the National Guard and later in the United States Army during World War I earning the rank of lieutenant, the Silver Star, and the Distinguished Service Cross.

[5] Republicans had held the seat from 1914 until 1936, when Democrat Frank W. Towey, Jr. won it on the coattails of President Franklin Roosevelt's re-election.

By early 1954, New Jersey Republican leaders had decided to withdraw party support for the incumbent senator, Robert C. Hendrickson.

Kean had secured commitments of endorsements from several key GOP leaders, but he declined to announce his own campaign until Hendrickson declared his intentions publicly.

[1] He won the Republican primary by 23,894 votes over Bernard M. Shanley, who had served as Deputy Chief of Staff to President Dwight Eisenhower.

Robert J. Morris, who had served as Chief Counsel to the United States Senate Subcommittee on Internal Security, finished third with 73,658 votes (20.72%).

[9] Kean made a political comeback in 1959, challenging incumbent William Yeomans for Republican Chairman in Essex County.

Kean organized a slate of reform candidates opposed to Yeomans headed by Alfred C. Clapp, a popular former state senator and judge.

Yeomans backed Essex County Prosecutor Charles V. Webb, Jr. for the State Senate, but Clapp won the nomination by a massive 20,000 vote margin (72%-28%).

Kean backed Bergen County State Senator Walter H. Jones, the losing candidate in the 1961 Republican gubernatorial primary.