It's expected to be one of the more interesting Wisconsin congressional races next year.
Republican Glenn Grothman has a reputation for being a staunch conservative in the state house and now Congress.
Grothman's voting record is now coming under scrutiny by a Democrat who wants his job.
"We're factchecking Dan Kohl who says that Glenn Grothman is the most-partisan member of the U.S. House of Representatives," said Tom Kertscher with the Milwaukee Journal Sentinel.
Dan Kohl is the nephew of former U.S. Senator Herb Kohl.
PolitiFact Wisconsin looked at the Grothman's voting record in Congress. Starting with the so called Bipartisan Index which looks at bills a lawmaker co-sponsors with members of the opposing party.
"By one measure, Grothman arguably is the most-partisan member of the House," said Kertscher. "However, that measure was from 2015-2016 and there are other ways of measuring partisanship."
Grothman's office tells PolitiFact Wisconsin he has worked with Democrats in this session on legislative issues like refinancing student loans.
So what about Kohl's claim?
"The important part of this factcheck is that there's not a single definition of partisanship," said Kertscher. "Being partisan means different things to different people and there are different ways to measure it."
So how would you rate this claim? The Truth O Meter ranges from Pants on Fire - which means false and ridiculous -- to True.
PolitiFact Wisconsin rated Kohl's claim - Half True. Meaning it's partially accurate.
