While many House Members used this past weekend to hit the campaign trail or to prepare for the last week before adjournment, Ohio Rep. Rob Portman (R) spent it holed up in Wyoming pretending to be a Senator from North Carolina.

For the second election in a row, Portman was asked by Vice President Cheney to be his sparring partner during pre-debate preparations. Having played the part of Sen. Joe Lieberman (D-Conn.) in 2000, Portman has now taken on the role of Sen. John Edwards (D-N.C.) in the run-up to the vice presidential showdown on Tuesday at Case Western Reserve University in Cleveland.

Portman’s job — much like the task of Sen. Judd Gregg (R-N.H.), who has played the part of Al Gore and Sen. John Kerry (D-Mass.) for President Bush — is not so much to imitate the Democrats’ mannerisms but to anticipate what they would say in specific debate situations.

Of course, that didn’t stop Portman last time around from trying what he called “my weak attempts” at a Lieberman impression during the 2000 practice debates, one of which took place at a Wild West-themed theater in Wyoming.

The key to such sessions, Portman said, is to be as challenging and aggressive as possible, so that the real debate won’t hold any surprises for Cheney.

Portman is credited by his “opponent” with doing a good job in 2000. On the wall in his Capitol office, Portman has hung a mock poster likening the Cheney-Lieberman debate to a boxing match. Cheney autographed it for him, writing, “Rob, you were tougher than my opponent.”

Portman was hesitant to discuss details of this year’s debate preparations or to spend much time trying to set expectations for the Cheney-Edwards matchup. But he did — as each side typically does to the other — make a point of praising the former trial lawyer’s debating skills.

“I expect Senator Edwards to be a very good communicator,” Portman said.

Having complimented Edwards’ speaking abilities, though, Portman couldn’t resist a dig at the alleged tendency of Edwards and Kerry to flip-flop.

Lieberman “and Vice President Gore didn’t shift their positions so much,” Portman said. “The difficulty is knowing what positions Senator Edwards will take on some issues.”

Portman was aided in 2000 by the fact that Lieberman had been in the Senate for several years and had a considerable record to study. Lieberman also was knowledgeable enough about policy that he could formulate answers without being scripted.

Negatively contrasting Edwards with his 2000 predecessor, Portman called Lieberman “a thoughtful legislator.”

“It was harder to know what he would say in the debates,” he said. “It was a little more of a challenge.”

To prepare for his time as Edwards, Portman watched videos and listened to audiotapes of the Senator’s speeches. Portman also read Edwards’ book, “Four Trials.”

While Portman did plenty of preparation for the weekend’s practice session, he said Cheney needed less handling than many candidates do in similar situations.

“The reason that Dick Cheney did so well four years ago was that he was not scripted,” Portman said.