U.S. Rep. Adam Kinzinger, R-Channahon, and Lt. Gov. Evelyn Sanguinetti watch as commercial fishermen and scientists from the Illinois Department of Natural Resources demonstrate how fishermen in Joliet inhibit the spread of the invasive Asian carp March 26, 2018, at Rock Run Rookery in Joliet.
U.S. Rep. Adam Kinzinger, R-Channahon, and Lt. Gov. Evelyn Sanguinetti watch as commercial fishermen and scientists from the Illinois Department of Natural Resources demonstrate how fishermen in Joliet inhibit the spread of the invasive Asian carp March 26, 2018, at Rock Run Rookery in Joliet.

Despite being critical of President Donald Trump at times, U.S. Rep. Adam Kinzinger will not have a primary opponent in the 16th Congressional District.

The filing period expired Monday with no other other Republicans entering the race.

Kinzinger, R-Channahon, filed his candidacy as early as allowed Nov. 25, collecting more than 4,000 signatures. Dani Brzozowski, of La Salle, and Benjamin Baer, of Coal City, filed for the Democratic nomination, meaning they will face each other in the March 17 primary.

Politico labels the 16th District as "likely Republican," meaning Kinzinger's greatest challenge could have come from within his own party. By numbers alone, the 16th District had 65,520 Republican voters come out for the midterm primary, compared to 41,663 in the Democratic race.

"In a normal year, most of the 'likely' seats do not end up very close, let alone flipping," said Brian J. Gaines, a political science professor at the University of Illinois. "For Kinzinger to have escaped a primary challenge is probably the most important step in getting re-elected. Trump is an unpredictable president to be sure, but he has too many critics of varying intensity to pick fights with every single one."

Not garnering a primary opponent is not unusual, however, for Kinzinger, who has $1.5 million on hand in his campaign coffers. He ran uncontested in 2016 when Republican Colin McGroarty was removed from the race prior to the primary.

Two years ago, Kinzinger was opposed in the GOP primary by James Marter, of Oswego. Kinzinger garnered 67.9% of the vote. Marter, who lost in a prior GOP primary to Mark Kirk for U.S. Senate, opted to run in the neighboring 14th Congressional District race.

In 2014, Kinzinger bested David Hale by tallying 78.4% of the vote. Two years before that, Kinzinger took control of the 16th District by defeating incumbent Don Manzullo, R-Rockford, with 53.9% of the vote.

While not in favor of impeachment, Kinzinger has been critical of the president's comments on Twitter. He called on the president to redact a post referencing "lynching" and called another one of his tweets that mentioned a Civil War-like fracture if the president was removed from office "beyond repugnant." He's also been critical of the president's decision to remove U.S. troops from Syria where they were supporting Syrian Kurds.

Kinzinger has been called a moderate by critics within the Republican party.

Kinzinger was one of five Republican congressmen from Illinois who was not named an honorary co-chairman of the Trump re-election effort in 2020. Kinzinger told the Chicago Tribune he believes the decision was likely made by Trump's operatives, saying he believes he has a good relationship with the president.

According to FiveThirtyEight, Kinzinger votes 83% of the time in line with the president's position.

After flipping Democrat in the midterm, the neighboring 14th District has drawn seven GOP candidates, perhaps away from Kinzinger's district.

Naperville Democrat Lauren Underwood, a health care policy expert who worked on the Affordable Care Act as a part of the Obama administration, defeated Randy Hultgren, R-Plano, regaining a seat for Democrats that Hultgren held since 2011.

State Sen. Sue Rezin, R-Morris, whose district includes Ottawa and Streator, joined the race, despite residing within the 16th Congressional District, just miles away from the district boundaries.

Her opponents are Rep. Jim Oberweis, R-Sugar Grove; financial futures trader Ted Gradel, of Naperville; Kendall County Republicans Chairman James Marter; Catalina Lauf, of Woodstock; Jerry Evans, of Warrenville; and Anthony Catella, of St. Charles.