Republican presidential candidate Mitt Romney on Saturday predicted a victory in Wisconsin's upcoming primary contest and said he believed it could help put him on a path to clinching the nomination.

Romney, a former Massachusetts governor, has come from behind in the polls in Wisconsin to take the lead over chief rival Rick Santorum. The state will vote on Tuesday along with Maryland and Washington, DC.

"This was an uphill battle for me if you looked back three or four weeks ago. 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 said.

The normally cautious candidate voiced confidence about his campaign in speaking to volunteers who were making telephone calls on behalf of the state's embattled Republican governor, Scott Walker, who is the target of a recall effort.

"It feels pretty good in Wisconsin today," Romney said, appearing for the second day in a row with Wisconsin's popular congressman Paul Ryan, seen as a potential vice presidential nominee on the Republican ticket.

A Romney victory in Wisconsin, combined with wins in Maryland and Washington, DC, would widen his lead over Santorum in delegates for the nominating convention in Tampa in August and make it nearly impossible to catch the frontrunner.

Romney leads in the polls in all three states.

"If you do your job and I do mine, I might be able to pick up all three of those and that would obviously be a big statement," Romney said.

The Milwaukee Journal Sentinel, Wisconsin's largest newspaper, endorsed Romney for the Republican presidential nomination on Saturday.

In the state-by-state battle to accumulate the 1,144 delegates needed to win the nomination, Romney has an estimated 565 delegates, according to Real Clear Politics, followed by Santorum with 256, former US House of Representatives speaker Newt Gingrich with 141 and congressman Ron Paul with 66.

Romney on Friday had pivoted to a general election matchup between him and President Barack Obama and began looking ahead to the Nov 6 election against the Democratic incumbent.

Asked by a reporter whether he was now in a general election mode, Romney insisted he was taking nothing for granted but voiced confidence about avoiding a scenario where no candidate wins enough delegates for the nomination and the battle is decided at the Republican convention.

If he wins Wisconsin, he said, "I think we'll be on a path that will get me the nomination well before the convention - sure hope so."

The next big primary date, April 24, looms as increasingly important with six states to vote and Romney expected to win at least five of them. Santorum's home state of Pennsylvania is the only question mark, and Romney aides made clear Romney plans an aggressive campaign there.