ST. JOSEPH, Mich. (AP) — Michigan Republican congressman Fred Upton announced Monday he will seek re-election to his Sixth Congressional District seat located in the southwest corner of the state.

In announcing his bid for an 18th term, Upton said there is “unfinished” business that has to be completed, including fighting the opioid epidemic and immigration reform.

“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 in a statement. “Despite what you hear, there are good people in both parties doing good work. We just need more of them.”

Upton has served under five presidents during his more than 30 years in Congress. His re-election campaigns have emphasized what he calls “common-sense values” and bipartisan accomplishments.

Upton, 66, was being watched closely as a potential House retiree as Republicans attempt to regain the chamber majority in the November elections.

He entered the House in 1987.

But while several departing GOP lawmakers have included the frustrations of being in the chamber’s minority among their reasons for leaving, Upton said in an interview that the rise of Sen. Bernie Sanders, I-Vt., as front-runner for the Democratic presidential nomination “probably” was a factor in his decision to run again. Many Republicans believe a Sanders nomination would dramatically increase their chances of capturing House control.

Upton told The Associated Press he believed Sanders would hurt the campaigns of down-ballot Democratic candidates, saying Sanders is “too much to chew on” for many Michigan voters.

Twenty-seven Republicans are not seeking reelection to the House, and four others have already resigned and left office. The GOP will need to gain 18 seats to take over the House, assuming it retains several vacant seats it formerly controlled.

Upton voted against the impeachment of President Donald Trump. Before casting his vote, Upton called the impeachment process “highly partisan and clearly motivated by what I believe is an attempt to overturn the last election.”

Trump was accused of abusing his power by asking Ukraine to investigate his 2020 rival, Joe Biden, while holding military aid as leverage. He also was accused of obstructing Congress by blocking the House’s efforts to probe his actions.

Upton served as chairman of the House Energy and Commerce Committee from 2010 to 2016, and he is currently the vice chair of the Problem Solvers Caucus. His southwest Michigan district includes Berrien, Cass, Kalamazoo, St. Joseph and Van Buren counties and most of Allegan County.