GOP vice presidential nominee Rep. Paul RyanPaul RyanPaul Ryan sells out conservatives with healthcare surrender GOP lawmaker calls for select committee on Russia Matt Schlapp: 5 lessons Trump, Ryan must learn from healthcare debate MORE (Wis.) will hold his first all-day debate preparation session this weekend.

Campaign aides said Ryan would meet with advisers in Oregon on Sunday and begin preparing for his debate with Vice President Joe BidenJoe BidenPaul Ryan sells out conservatives with healthcare surrender Senate about to enter 'nuclear option' death spiral Biden: I regret not being president MORE, according to reports. 

“Our initial focus was having a smooth rollout of the vice presidential nominee," an aide told ABC News. "The primary focus following that was the convention speech. Since the convention, we have shifted so that preparing for the vice presidential debate is probably the highest-profile event for the vice presidential candidate from now until the election."

The aides told ABC that Ryan and his advisers are “intensely focused” on preparing and do not intend to “take the challenge lightly.”

One of the advisers called Biden, who served 36 years in the Senate before assuming the vice presidency “one of the most experienced debaters in American political life.”

Aides said Ryan was reviewing a set of white binders with briefings on different policy areas and editing them to insure that he was comfortable with his debate points and could present them in his own voice. 

The campaign has yet to reveal who Ryan’s stand-in for Biden will be, but reports said the debate partner would not be present at the first prep session. 

Rep. Chris Van Hollen (D-Md.), Ryan’s colleague on the House Budget Committee will play him in Biden’s debate prep.

Earlier this week, Van Hollen called Ryan a “good debater” and said he would urge Biden to press Ryan on the “facts” of his budget.

"I think Paul is a good debater, the question is the use of facts on the budget," Van Hollen said on Fox News. "I think we're going to hear a lot more about that: as you know, with his acceptance speech there was a lot of fact-checking going on the next day."

Democrats have hit Ryan, claiming he wrongly blamed Obama for the closure of a General Motors plant in his hometown of Janesville Wis. during his acceptance speech at the GOP convention. The plant though was shuttered after Obama’s election but before he assumed the presidency. 

Ryan has defended those remarks, claiming he did not blame Obama for the plant closing down and that the closure only highlighted Obama’s failure to keep his campaign promises. 

The Ryan-Biden debate is slated for Oct. 11 and will be moderated by ABC News correspondent Martha Raddatz.

Romney campaign advisers also joked that Ryan’s debate prep would cut into his time to watch his Green Bay Packers who open their 2012 NFL season Friday. “We will give him a little bit of a break in the middle of the day to watch the Packers game – but not much,” a Romney aide said, according to reports. "We are negotiating right now how much of it he gets to watch."

Romney spent last week, while media attention was focused on the Democratic National Convention in Charlotte, N.C., at the home for former Massachusetts Lt. Gov. Kerry Healey in Vermont preparing for his own three debates with Obama. 

Sen. Rob PortmanRob PortmanMcCaskill investigating opioid producers Overnight Finance: Senators spar over Wall Street at SEC pick's hearing | New CBO score for ObamaCare bill | Agency signs off on Trump DC hotel lease GOP senators offer bill to require spending cuts with debt-limit hikes MORE (R-Ohio) who was rumored to be on Mitt Romney’s vice presidential shortlist will stand in for President Obama in Romney’s mock debates.