In case there was any doubt that Ohio Treasurer Josh Mandel is the frontrunner to become the GOP Senate nominee, Sen. Rob Portman said Monday that he is backing Mandel in the race to take on Sen. Sherrod Brown (D).

“I’m helping Josh,” the freshman Republican told the Columbus Dispatch on Monday. “I guess I haven’t officially endorsed him yet, so I guess this is a news opportunity. But I’m helping Josh. I don’t know if anybody else is going to get in. I think his fundraising in the second quarter has been pretty impressive. I think he’s a good candidate. He also understands that the message has to be the economy and jobs.”

Portman added that he already met with Mandel about his bid, saying, “He’s not shy and retiring.”

Mandel has collected several big-name endorsements over the past couple of months, including from the Club for Growth and Sen. Jim DeMint’s (R-S.C.) Senate Conservatives Fund.

Former state Sen. Kevin Coughlin is the only other Republican seeking the nomination to challenge Brown. However, at least one other Buckeye Republican suggested Rep. Jim Jordan (R) should consider challenging Brown too.

Former Ohio Secretary of State Ken Blackwell, a Republican who declined to run for Senate earlier this year, talked up Jordan as a Senate candidate if his House seat is eliminated through redistricting. Local news outlets suggested Jordan’s district is on the chopping block after the Republican Study Committee chairman’s split with Speaker John Boehner (R-Ohio) over the recently passed debt ceiling deal.