After his father's death, his mother moved from Hillside to Bloomfield, New Jersey, where she supported the family by working as a clerk at the Sunshine Biscuits warehouse.

His mother, suffering from lymphoma, required paramedics to take her from Columbia Presbyterian Hospital to the school auditorium on a stretcher to hear the address.

[2] In 1973, he was elected to the Common Cause National Governing Board, a nonpartisan, nonprofit advocacy group and think tank with the mission to make political institutions more open and accountable.

He also championed campaign finance reform, working closely with Thomas Kean, then a member of the New Jersey General Assembly.

[3] In 1990, Zimmer ran for the United States House of Representatives for the 12th District, then encompassing parts of Hunterdon, Mercer, Somerset, Morris and Warren counties.

The seat was open after six-term incumbent Jim Courter decided to not seek reelection after unsuccessfully running for Governor of New Jersey the previous year.

In the Republican primary, Zimmer defeated Assemblyman Rodney Frelinghuysen, the early favorite, and Phil McConkey, former wide receiver for the New York Giants.

It was named after Megan Kanka, a New Jersey resident who was raped and murdered by convicted sex offender Jesse Timmendequas.

As a member of the Environment Subcommittee, he introduced environmental risk-assessment legislation later incorporated in the 1996 amendments to the Safe Drinking Water Act.

[3] In 1995, Zimmer lined up support to run in the following year's United States Senate elections, becoming the front-runner among Republicans seeking to face Democratic incumbent Bill Bradley.

[8] Zimmer formally announced his candidacy on February 13, 1996, having already secured the endorsement of Governor Christine Todd Whitman and other leading Republicans.

Party leaders had originally supported businesswoman Anne Evans Estabrook for the Senate nomination until she withdrew in March 2008, following a mini-stroke.

Unanue received criticism in the race because of his residency in New York City and his spending his entire three-week campaign in Vail, Colorado.

In polls conducted by Rasmussen Reports and Strategic Vision in mid-September 2008, Zimmer trailed Lautenberg by 7 points.