Pennsylvania, a Look at Romney's Ground Game

(Image Credit: Stephan Savoia/AP Photo)

MILWAUKEE - Looking ahead to what will be the next big primary, the Romney campaign is wasting no time setting up in Pennsylvania.

The home state of Sen. Rick Santorum, Pennsylvania offers a unique opportunity for the Romney campaign, which could look to end the long primary season with a substantial win in the Keystone State.

The Romney campaign has set up a campaign headquarters in capital Harrisburg and four paid staffers are already in the state.

Expect an influx of staffers to join after tonight's primary in Wisconsin.

In addition, Romney has plans to campaign in the state as early as this week, with fundraisers and other events in the state expected throughout the month.

Santorum has already arrived in Pennsylvania, and has dubbed the state a "must-win" for his campaign.

Pennsylvania, Rhode Island, New York, Connecticut and Delaware hold primaries April 24.