House Speaker Paul Ryan (R-Wis.) is hitting the campaign trail this weekend — on behalf of Wisconsin Republican Sen. Ron Johnson's re-election bid.

GOP vice presidential candidate Indiana Gov. Mike Pence will join them Saturday morning at an event at Field Park in Mukwonago, Wisconsin, Politico reported Friday.

Ryan has had a tenuous relationship with the campaign of Republican presidential nominee Donald Trump, with his appearances on the GOP standard-bearer's behalf few and far between. Ryan has often criticized Trump for statements he's made about women and minorities and refused to endorse the candidate for months after his nomination.

The event is part of a bus tour for Johnson, who's polling at an average of 2.7 percentage points behind his Democratic challenger, Russ Feingold.

Fellow Wisconsin Republicans Gov. Scott Walker and Rep. Jim Sensenbrenner will also make appearances at the campaign event.