COUNCIL BLUFFS, Iowa - In his first comments about his debate next week against Rep. Paul Ryan, Vice President Joe Biden said he's focusing his prep on ensuring he has all his facts straight.

"What I've been doing mostly, quite frankly, is studying up on Congressman Ryan's positions on the issues, and Gov. Romney has embraced at least everything I can see. I don't want to say anything in the debate that's not completely accurate," Biden told reporters outside a Hy-Vee in Council Bluffs, Iowa.

"For example," he added, "I've been saying to you all that Gov. Romney has embraced the Ryan budget. Well, he has. He's gone back and said, no, he agrees with it. I just want to make sure when I say these things that I don't have the congressman saying, 'No, no, no, I don't have that position,' or, 'That's not the governor's position.' So it's mainly getting the factual predicates … on key issues on which Gov. Romney has spoken and Congressman Ryan has acted."

Biden has held two mock debate sessions with Rep. Chris Van Hollen, D-Md., who is playing Ryan, R-Wis., in debate prep.

The vice president praised President Obama's performance at the first presidential debate Wednesday in Denver and noted that it's difficult to anticipate what position Mitt Romney will take on certain issues.

"I thought the president did well," Biden said. "He was presidential. I think that you just never know what game, what position Gov. Romney's going to come with. I mean, you know, the centerpiece of their economic policy so far has been their tax cut, and last night we found out he doesn't have a $5 trillion tax cut, and I guess he outsourced that to China or something. I don't know if that's offshored. … But it's hard to figure out what Gov. Romney's position is on a number of issues.

"But I think as time goes on, meaning days, it's going to become pretty clear that Gov. Romney has either changed a number of his positions or didn't remember some of his positions," Biden said. "And I think at the end of the day, we have two more debates coming up, the president does, and I feel really good about it."

Asked if Wednesday's debate raised expectations for his own match-up with Ryan next week, the vice president said he's looking forward to sparring with Ryan, but suggested such situations are not easy.

"All debates are tough," he said. "You can sit there and say, 'You know, I would have done that and I would have done this.' You hear people saying that. Well, it is nothing like standing up before 20-, 30-, 40-, 50-, 60-, 70 million people.

"All debates are tough, but I am looking forward to it. I really am," he said. "The thing about Congressman Ryan is he has been straightforward up to now about everything - all the significant changes he wants to make. We have a fundamentally different view on a whole range of issues. So I hope it will be a good debate."