TAMPA, Fla. – He didn’t get the call to join Mitt Romney on the Republican ticket, but Ohio Sen. Rob Portman appears set to play a key role getting the Romney agenda passed next year.

While Portman has been mentioned as a likely Cabinet pick Рpotentially Treasury secretary Рthe Ohio lawmaker with the golden r̩sum̩ believes he could be more valuable to a President Romney in the Senate, which will remain sharply divided next year under even the most optimistic outcome for the GOP.

“I plan to stay where I am,” Portman said in an interview after speaking at the Ohio delegation breakfast at the Republican National Convention today. “I’ve focused a lot on breaking through the partisan gridlock and getting stuff done. I know that’s not what every Republican wants to talk about at a Republican convention, but, frankly, I’m worried about our country, and everything major that has to happen has to go through the Congressional process.”

Portman has experience reaching out to Democrats – coauthoring bipartisan bills on regulatory reform, energy efficiency and the like. He has strong ties in both chambers and unrivaled expertise in the budget and tax matters that would quickly embroil the new administration. He is also close friends with Romney’s running mate, Rep. Paul Ryan (Wis.), from their days together on the Ways and Means Committee, and he knows how to work the process at both sides of Pennsylvania Avenue from his stints as budget director and trade representative.

Indeed, those attributes kept him near or at the top of the veep list, along with the critical nature of Ohio’s 18 electoral votes in November. But he showed no signs today of any remorse at not being on the ticket, giving a rousing pitch to the Ohio delegation about fellow policy wonk Ryan.

Portman said he’s talked to Romney during the past year about getting his agenda through the Senate – with Romney asking about intricacies of the filibuster-busting reconciliation process to talking about the need to reach out to Democrats.

Portman said Romney’s focus on a strategy to accomplish his agenda was one reason Portman endorsed him early, in South Carolina.

“I became convinced that he was the right Republican candidate to be able to work with Congress and achieve results. … He gets it,” Portman said, noting Romney already worked with Democratic lawmakers in Massachusetts.

He likened a Romney victory to Ronald Reagan winning in 1980. “He was able to reach out to Republicans and boll weevil Democrats, I guess we would call them moderate Democrats, and achieve great things for our country. That’s the potential.”

Obama, by contrast, has failed to provide the leadership needed to deal with the nation’s long-term problems, he said.

Portman has already seen several earlier efforts at dealing with the debt, entitlements and tax reform sputter, having a front-row seat on last year’s failed super committee. “I was probably the most naive member of that committee. I actually took it seriously,” he joked. “It’s got to be for real next time,” he said.

Despite Portman’s protestation that he plans to stay in the Senate, others have speculated that he would be a natural pick for a Romney administration and could be persuaded to join if he were given a broad enough portfolio and if Romney wanted him badly enough.

“It’s a great question,” said Rep. Patrick Tiberi (R-Ohio), a senior tax writer who would play a large role in passing a major tax overhaul next year.

The Treasury slot, with a mandate to take the lead on tax reform, could be enticing if the offer were made, some in the GOP have speculated.

“That would be pretty huge,” Tiberi said.

Portman would have to weigh that against being one of 100 and not having a key chairmanship.