(Image Credit: William Thomas Cain/Getty Images)

Vice President Joe Biden  next week will officially begin transitioning to his role as the leading surrogate for President Obama's re-election campaign, attending the first of a series of public events in battleground states aimed at shaping the general election narrative.

Biden will deliver a campaign speech in Ohio, where he will frame the key issues Democrats see as defining the 2012 race, a campaign official told ABC News.  The source, who spoke on condition of anonymity, could not confirm the date or the issues to be addressed but said more details would be forthcoming.

He will give three other speeches over the next several weeks, the official said. All will be free and open to the public, marking a new phase in the campaign's roll-out and effort to raise Biden's profile.

Biden, who the campaign has planned to feature prominently in its outreach to voters in blue- collar communities, has made two trips to Ohio this year, in addition to visits to Michigan, Pennsylvania, Iowa and New Hampshire.

The choice of Ohio as the site of Biden's first event underscores the importance of the state to Team Obama's electoral map.

Obama for America has ramped up operations in Ohio over the past few months, with a dozen paid staffers overseeing  nine field offices across the state and hundreds of volunteers engaging more than 650,000 voters, according to the campaign.  The Obama campaign has also gone on the air with TV ads in Ohio markets promoting the president's record and focusing attacks on Mitt Romney ahead of today's primary.