He graduated from Mary D. Bradford High School and went to work at the American Brass Company plant in Kenosha, following in the steps of his father and grandfather.

[2] He became chairman of the county board's health and human services committee; one of his major initiatives in that capacity was the establishment of the Shalom Center shelter and food pantry.

[1] In 1992, incumbent state representative John Antaramian was elected mayor of Kenosha and announced he would not run for re-election to the Assembly later that year.

He faced Kenosha city councilmembers Wanda Lynn Bellow and Stephen Casey in the September 1992 Democratic Party primary election.

Also attending and endorsing Wirch were state representative James Kreuser, mayor John Antaramian, and sheriff Allan Kehl.

Wirch faced an opponent in every election; his closest race was in 2004, when he won just 52% of the vote against Reince Priebus, who would later become chairman of the Republican National Committee and White House chief of staff.

One of the first legislative initiatives of the new governor, Scott Walker, was the so-called "Budget Repair Bill", which stripped state employee unions of their collective bargaining rights.

After the bill became law, Democrats attempted to capitalize on the outrage caused by the passage of the anti-union legislation and shifted to a recall campaign over the next year.

State political observers speculated that he received the seat in exchange for his vote for Chris Larson as minority leader.

[23] In 2017, Wirch was the only Democrat in the state Senate who voted in favor of the three billion dollar tax incentive package for the Foxconn in Wisconsin project.