James D. Oberweis (born June 10, 1946) is an American businessman, investment manager, and politician from the state of Illinois.

The former owner of Oberweis Dairy in North Aurora near Chicago, he served as a member of the Illinois Senate, representing the 25th district from 2013 to 2021.

[1][2] He received a Bachelor of Arts from Illinois, and then a Master of Business Administration from the University of Chicago.

[5] His father, Joe, had died in 1984, and Joe's successor (and Jim's older brother) John suffered an incapacitating stroke in 1986; after Jim's purchase he turned day-to-day operations over to outside presidents who embarked on acquisition programs highly leveraged with debt.

[3] Oberweis has sought elective office seven times, succeeding in the 2012 race for the 25th State Senate district seat.

Some Republicans felt that as the second-place finisher, Oberweis should replace Ryan, but the state central committee chose Alan Keyes instead.

Keyes lost to Barack Obama by the largest margin for the Illinois U.S. Senate race in history.

[12] Oberweis's 2004 campaign was notable for a television commercial in which he flew in a helicopter over Chicago's Soldier Field and claimed enough illegal immigrants came into America in a week (10,000 a day) to fill the stadium's 61,500 seats.

[15] The winner of the primary was Judy Baar Topinka, who was defeated by Democrat Rod Blagojevich in the general election 49.8%–39.3%, with Rich Whitney, the Green Party candidate, receiving a little over 10.3%.

[11] When U.S. Representative Dennis Hastert resigned his seat (Illinois's 14th congressional district) on November 26, 2007, Oberweis ran to replace him.

[4][17] In 2013, as State Central Committeeman, Oberweis led the effort to oust former Illinois Republican Party Chairman Pat Brady after his controversial public support of same-sex marriage.

[21] In the 2012 general election, Oberweis won the 25th State Senate seat previously held by Chris Lauzen, his former GOP primary rival in the 2008 congressional race.

Oberweis was the Republican nominee for the 2014 Senate election, for the seat held by Democrat Dick Durbin.

[29] Oberweis announced he would run again for Illinois's 14th congressional district, challenging Democratic incumbent Lauren Underwood.

[30] On March 17, 2020, he won the Republican nomination, narrowly defeating six other candidates including fellow state Senator Sue Rezin, and businesswoman Catalina Lauf.

[33][34][35] That same day, Oberweis began sending out fundraising appeals to fund fees associated with a potential recount.

[41] In January 2021, Oberweis filed a notice of contest with the U.S. House of Representatives, alleging that irregularities in the vote recount would make him the winner of the election.