The defeat of Arlen Specter in the Pennsylvania Democratic U.S. Senate primary comes 32 years after New Jersey Republicans rejected Clifford Case’s bid for a fifth term, and 37 years after incumbent Gov. William Cahill lost the Republican primary. Case and Cahill are the only incumbents to lose primaries in New Jersey history; Case lost to Jeff Bell, a former speechwriter for Ronald Reagan, 51%-49%, and Cahill was ousted by U.S. Rep. Charles Sandman (R-Cape May City), 58%-41%.
Others have faced serious primary challenges: U.S. Rep. Rob Andrews (D-Haddon Heights) took on incumbent Frank Lautenberg in the 2008 U.S. Senate primary, but lost 60%-40%; Gov. Brendan Byrne won renomination in 1973 with 30% of the vote against eleven challengers; and Harrison Williams beat then-State Sen. Frank Guarini (D-Jersey City) 66%-34% in the 1970 Democratic primary for U.S. Senator.
In 1924, Republican National Committeeman Hamilton Fish Kean (the grandfather of Gov. Thomas Kean), challenged incumbent U.S. Senator Walter Edge and lost the GOP primary, 57%-43%. Incumbent U.S. Sen. Joseph Frelinghuysen (a cousin of U.S. Rep. Rodney Frelinghuysen), won 69% in the 1922 GOP primary against George Record, a reformer and frequent candidate from Jersey City. Frelinghuysen lost his bid for a second term in the general election against Gov. Edward Edwards; Edwards lost his 1928 re-election bid to Kean.
The last incumbent congressman from New Jersey to lose a primary was Cornelius Gallagher (D-Bayonne). Gallagher was defeated by another Democratic incumbent, Domenick Daniels (D-Jersey City) after redistricting placed them in the same House district.