GOP front-runner Mitt Romney on Saturday predicted he would win Tuesday's critical Wisconsin primary, according to media reports.

Romney, the presumptive nominee, believes a win there could help him deliver a knockout blow to his chief Republican rival, former Sen. Rick Santorum (Pa.).

"This was an uphill battle for me if you looked back three or four weeks ago," said Romney at a campaign event in the state. "And now we're looking like we're going to win this thing on Tuesday, but I've got to have you guys get out and vote."

Romney leads Santorum in Wisconsin and the other two Tuesday primary battlegrounds: Maryland and Washington, D.C.

Victories there would add to the former Massachusetts governor's two-to-one advantage in delegates and make it more difficult for Santorum, former House Speaker Newt Gingrich or Rep. Ron Paul (Texas) to catch him before the convention. 

An NBC News-Marist poll released on Friday showed Romney with a solid seven-point lead in Wisconsin, with 40 percent support to Santorum's 33 percent. Paul had support from 11 percent of the likely GOP voters surveyed, trailed by Gingrich at 8 percent.

A Marquette Law School poll released earlier last week showed a similar edge, with Romney holding an 8-percentage point lead over Santorum.

Forty-two delegates are up for stake in Wisconsin's winner-take-all primary, and with Santorum not on the ballot in Maryland or Washington, D.C., Romney could sweep the night.

Romney's efforts in Wisconsin have been aided by the endorsement of party heavyweight Rep. Paul RyanPaul Davis RyanHenry Kissinger, Tim Cook among guests at White House state dinner Overnight Finance: Stocks fall hard | Trump sending delegation to China for trade talks | SEC fines Yahoo M over breach | Dodd-Frank rollback dominates banking conference To keep control of House, GOP must have McCarthy as next Speaker MORE (R-Wis.). Romney campaigned with the influential House Budget Committee chairman on Saturday.