WASHINGTON -- Ohio Sen. Rob Portman's biggest asset as a potential running mate for Mitt Romney has traditionally been seen as his depth of experience in government and knowledge of the economy.

But Portman, speaking to an audience of hundreds at the American Builder and Contractors Association conference here in Washington, tried his hand at an important secondary role for vice presidential nominees: attack dog.

The Ohio pol talked about the difficulties his father faced when he started a forklift dealership in Cincinnati when Portman was five-years-old, a risk he says he dad may not have taken today because of the "anti-business rhetoric" and regulations imposed by Democrats. Those hurdles were compounded on Monday, Portman said, by President Obama's call to let the Bush-era tax cuts expire for Americans making over $250,000.

"We saw it again yesterday, just right across the way here," Portman said at the Capital Hilton, located just blocks from the White House. "We had the president of the United States telling us again that the way to get out of these economic problems we’re in is to raise taxes on small business owners. And some of them are in this room."

For all of his efforts to sharpen his rhetoric toward the president, Portman's edge was less pronounced than some of the other rumored short-listers, namely Florida Sen. Marco Rubio or New Jersey Gov. Chris Christie.

"We gave him the ball," Portman said of the president. "The American people gave him the ball. At a time when he was inheriting a tough economy, let's be honest. But in my view he fumbled the ball.  It's time to give the ball to somebody else who has a game plan whose got a strategy to be able to turn things around, who understands because he has the experience and a record and the public policy positions to do it.  That's why I'm supporting Mitt Romney."

There was no crescendo in his voice, and admitting that Obama inherited "a tough economy" is not on any list of GOP talking points. But his mild manner is often cited as a reason why Portman is so well-liked on both sides of the aisle.

Though Portman may have trouble stirring up more than moderate applause in front of big crowds, it likely is of little consequence to the presumptive Republican nominee. Romney is believed to be looking for someone with the readiness to serve as commander in chief, and Portman's time in the House and Senate, along with serving as U.S. trade representative and director of the Office of Management and Budget fits the bill.

Upon exiting the conference this morning, Portman told ABC News that he had met with Romney aides while in Boston a day earlier raising money for the Romney Victory fund.  A Portman aide told NBC that the face-to-face time was for "fundraising meetings and financial events” and downplayed the notion he was there for anything related to the vetting process.

And while other Romney surrogates may be able to fire up a group of supporters, few can be as specific as Portman when it comes to how to fix the economy.

Along with lowering the tax burden on small businesses, Portman urged to reform a tax code that is "now 9 times longer than the Bible, and not nearly as interesting." For as bad as things might be now, the senator said all is fixable with the right leadership.

"We all love this country. I think the president loves this country.  I believe he thinks he's doing the right thing. But frankly, I dont think he gets it."