Gov. Robert F. McDonnell of Virginia addressed the Republican National Convention on Tuesday not once but twice, first as chairman of the platform committee and then in prime time as leader of a must-win state.

That morning, when he could have been practicing one speech or the other, he schlepped 25 miles from Tampa to a Holiday Inn in Clearwater to speak to a joint breakfast of the Montana and Washington state delegations. He was there in another capacity, as chairman of the Republican Governors Association, to plug GOP candidates for governor in those states.

“He’s the governor of a battleground state, chairman of the RGA, head of the platform committee, and he speaks twice,” McDonnell spokesman Tucker Martin said by e-mail. “He’s wearing more hats than you’d see at the Kentucky Derby.”

Some say that McDonnell, with less than a year and a half left in the governor’s mansion, is playing yet another role in Tampa: that of a term-limited politician. Once mentioned as a potential running mate on Mitt Romney’s ticket, McDonnell could now be auditioning for a Cabinet position or a presidential run of his own.

“What you’re looking at right now at the Republican National Convention are the rising stars of the Republican Party,” said Pete Snyder, a Virginia technology entrepreneur and chairman of the 2012 Virginia Victory Campaign. “You’ll have Mitt Romney, who’ll be nominated [Tuesday]. You’re going to have a whole lot of focus on Paul Ryan. . . . But if you look lower down the list, it’s all the people who are going to be part of the Republican Party’s future — [New Jersey Gov.] Chris Christie, Governor McDonnell.”

Virginia Governor Bob McDonnell addresses delegates during the Republican National Convention in Tampa, Fla. (Charlie Neibergall/AP)

Noting that Virginia governors can’t serve successive terms, Snyder added: “You don’t get a lot of runway when you’re governor of Virginia. You only have four years. And in a very short period of time, he has become a national player.”

Whether there is anything to the Cabinet or presidential speculation — Martin declined to comment on it — it’s certain that this week, McDonnell is Virginia’s multitasker in chief. The man who ran on the slogan “Bob’s for Jobs!” is juggling a tremendous number of them himself.

McDonnell’s most prominent role came shortly before 9 p.m. Tuesday, when he contrasted the nation’s struggling economy with Virginia’s relatively healthy one.

“Conservative fiscal policies are working, and so are more Americans in the states with Republican governors today,” McDonnell said. “Now, just think what we could do if we had a president who would support us, not obstruct us.”

McDonnell’s prominence has given Virginia Republicans considerable pride as they head into the final weeks of a neck-and-neck campaign between Romney and President Obama, who took the state four years ago.

Del. L. Scott Lingamfelter (R-Prince William) predicted that the Virginia delegation would be “all up on the chairs” cheering McDonnell in the convention hall — even as he noted that McDonnell was not the main point.

“I think it’s not so much what it means to Bob — I think he would say the same — but what it means for the country,” he said.

McDonnell’s high profile has given Democrats an opportunity to take a few shots.

“I think he’s one of many Republicans there trying out for 2016,” said Del. Mark D. Sickles (D-Fairfax). “One thing that’s always curious for Democrats is why Republicans never want to go back to the vaunted private sector that they talk about so much.”

Brian Coy, spokesman for the Virginia Democratic Party, said via e-mail: “If the governor were half as good at serving the commonwealth as he is at currying favor with the tea party, Virginians wouldn’t be sitting in traffic and sending their kids to overcrowded classrooms while he defends forced ultrasounds [before abortion] and ending Medicare as we know it on television.”

Even the governor’s admirers concede that his time in the spotlight does not come without risk.

“You carry the state, you’re a hero,” said former Republican congressman Tom Davis. “Who knows if Romney wins what that portends, or if he loses.”

Davis said he thinks that McDonnell would be “a great attorney general or secretary of commerce,” given his focus on job creation as governor and his background as a former state’s attorney general and prosecutor.

But he brushed off suggestions that McDonnell might be “auditioning” for such a position, since he and Romney are well acquainted.

As chairman of the platform committee, McDonnell had to get activists from across the country to agree on what it means to be a Republican, then sell it to the nation — all amid an uproar over a Missouri Republican’s comments about abortion, rape and pregnancy.

His swing-state governor duties have required countless interviews. He did 11 on Monday alone, wrapping up the last at 11 p.m.

He’s also devoted time to his RGA gig, promoting GOP gubernatorial candidates and conducting what was described as a “rolling RGA meeting” with staffers trailing him from one appointment to the next.

All that comes on top of gubernatorial duties that he’s carried out from afar. As Hurricane Isaac approached the Gulf of Mexico, McDonnell called Chief of Staff Martin Kent to discuss what state resources could be dispatched to affected states. He also spoke by phone with Louisiana Gov. Bobby Jindal (R) and Florida Gov. Rick Scott (R) to see whether there was anything he could do for them.