When Mitt Romney hits the trail in Evansville, Ind., on Saturday, he’ll be joined by Richard Mourdock, the tea-party-backed state treasurer who in May trounced six-term Sen. Richard Lugar to clinch the Hoosier State’s GOP Senate nomination.

Presumptive GOP presidential nominee Mitt Romney. (REUTERS/Las Vegas Sun/Steve Marcus)

Back in the spring, Romney declined to wade into the competitive GOP primary, even as other top Republicans, including former senator Rick Santorum (Pa.) and former Alaska governor Sarah Palin, backed Mourdock over Lugar. Among those supporting Lugar was Sen. John McCain (R-Ariz.).

Saturday’s event is the latest indication that the divisions that arose during the intraparty battle have given way to unity. Earlier this week, Lugar invited Mourdock to be the guest of honor at Senate Republicans’ weekly policy luncheon.

Mourdock is favored to best Rep. Joe Donnelly (D) in November; several national handicappers have rated the seat “lean Republican.”

Even so, Democrats believe they have a strong nominee in Donnelly, who has sought to play up his bipartisan credentials by linking himself to Lugar in his most recent TV spot.

Later Saturday, Romney is expected to attend a fundraiser at the home of businessman Steven E. Chancellor, chief executive officer of the American Patriot Group.

According to Reuters, Senate Minority Leader Mitch McConnell (R-Ky.) and former vice president Dan Quayle are among those expected to attend.

The Democratic super PAC American Bridge welcomed news of the joint appearance by circulating a Web site, WhoIsRichardMourdock.com, slamming the Senate nominee for what it describes as his “extreme views.”