U.S. Rep. Fred Upton, a St. Joseph Republican who's increasingly become a Democratic target, will run for an 18th term in the U.S House, he said Monday night.

The decision by Upton, who said he had "unfinished business," ensures that Republicans will have a well-funded incumbent to run in what could be a competitive southwest Michigan district. In 2018, a year when Democrats flipped two other U.S. House seats in the state, voters re-elected Upton by 4.5 percentage points.

"My wife and I earlier this month became grandparents for the first time, and this influenced our final decision. Some folks thought I might not run because I became a grandfather," Upton said in a statement. "But actually, I'm running because of it. And I am committed to working with anyone who's willing to help build a better future for our kids and grandkids."

Upton represents the 6th District, which includes Kalamazoo, St. Joseph, Berrien, Cass and Van Buren counties and most of Allegan County. He announced his re-election bid at an annual 6th District GOP event in Plainwell on Monday, according to his campaign.

While Upton was widely expected to seek re-election and had continued to raise money for his campaign, some Republicans questioned why he hadn't made an official announcement. On Monday, less than two months before the filing deadline, he put those questions to rest.

Known as a moderate Republican, Upton has, at times, publicly disagreed with President Donald Trump. He said his "unfinished business" included fighting the opioid epidemic, immigration reform and protecting the Great Lakes. He also touted his willingness to work across the aisle in the statement announcing his re-election campaign.

"I am raising my hand and committing to work with anyone of any party to deliver results, protect our communities and simply solve problems," Upton said, adding, "Despite what you hear, there are good people in both parties doing good work. We just need more of them."

State Rep. Jon Hoadley, D-Kalamazoo, hopes to challenge Upton in the November general election. Democratic Gov. Gretchen Whitmer endorsed Hoadley in a video posted on social media Friday.

Whitmer called Hoadley "a tireless advocate for cleaning up our environment" and "expanding health care."

Upton has reported raising $1.3 million for his 2020 campaign as of the end of 2019. To start the new year, he had $833,512 available. Hoadley has raised $734,190 with $246,731 on hand to start the year.

Upton defeated Democrat Matt Longjohn, a newcomer to politics, in 2018, which was the incumbent's closest re-election race in decades.

cmauger@detroitnews.com