MILWAUKEE — The shape of a general election battle between Mitt Romney and President Obama came into sharper focus Sunday as Vice President Joe Biden led an administration assault on the potential Republican nominee.

Biden took on Romney across a wide array of topics in a television interview, describing him as out of touch with the middle class and out of his depth on foreign affairs.

And in a rare break from her retreat from partisan politics, Secretary of State Hillary Rodham Clinton called Romney’s perspective on Russia “somewhat dated.” Romney recently called Russia the “No. 1 geopolitical foe” of the United States.

Obama’s reelection team has long assumed that Romney would emerge as the president’s Republican challenger. But after three months of party contests covering more than half the nation, conservative insurgent Rick Santorum is still blocking the former Massachusetts governor from fully claiming the title of presumptive nominee.

With the hard-fought Wisconsin primary two days away, Romney continued Sunday to try to cement an impression of inevitability.

At a pancake breakfast in Milwaukee, Romney cast the fall campaign against Obama as “a dramatic choice about what America’s going to be like.” A second term for Obama would mean “high unemployment, wage stagnation, vulnerability militarily … and a threatened future with potential catastrophe, economically.”

Romney also presented the latest in a long line of high-profile supporters: Sen. Ron Johnson, the tea party favorite who ousted Wisconsin Democratic icon Russell D. Feingold in the Republican sweep of 2010.

“I just want to assure every conservative, I’ve spoken with Mitt; I totally believe he is committed to saving America,” Johnson said at the breakfast with Romney and Rep.Paul D. Ryan, the candidate’s best-known Wisconsin supporter.

Pressure to coalesce around Romney also came from one of the nation’s top Republicans, Senate Minority Leader Mitch McConnell of Kentucky. Asked about Romney on CNN, McConnell called him “an excellent candidate” — albeit one he has not personally endorsed.

“I think the chances are overwhelming that he will be our nominee,” McConnell said. “It seems to me we’re in the final phases of wrapping up this nomination. Most of the members of the Senate Republican conference are either supporting him or they have the view that I do — that it’s time to turn our attention to the fall campaign and begin to make the case against the president of the United States.”

Unbowed, Santorum told Fox News that he had no intention of stepping out of Romney’s way, regardless of the result in Wisconsin. He planned to begin campaigning shortly in Pennsylvania, the site of an April 24 primary and a state he once represented in the Senate.

“We need a conservative,” Santorum told anchor Chris Wallace. “We need someone who can be a contrast with Barack Obama, not the same old tired establishment person that’s going to be shoved down our throat.”

Like Biden, Santorum has argued that Romney, a wealthy former corporate takeover executive, fails to grasp the hardships of average Americans. In a week of darting across Wisconsin’s vast dairy farm landscapes, Santorum has underlined the point with stops at small-town diners and bowling alleys. Sunday’s itinerary included Pla-Mor Lanes in Chilton and a riverside brewery in West Bend.

To the delight of Democrats, Santorum has also forced Romney to stay focused on social issues. On Fox, Santorum ridiculed Romney for running a TV ad “trying to convince the voters of Wisconsin — believe this one, Chris — that I’m not pro-life.”

On CBS, Biden waded into the political brawl over contraception and the Roman Catholic Church. Biden, who is Catholic, criticized Romney and other Republicans for objecting to the new federal rule requiring that health plans for employees of religious institutions, such as Catholic hospitals, cover contraception.

In essence, Biden said, the Republicans are telling women, “You can’t use birth control,” a stand he described as “totally out of touch with reality” and “the right of women to decide for themselves whether or not they want to use contraception.”

“I just find it remarkable that the argument’s even taking place,” he said.

As for Romney’s economic outlook, Biden said, “I can’t remember a presidential candidate in the recent past who seems not to understand, by what he says, what ordinary middle-class people are thinking about and are concerned about.”

He mentioned Romney’s comment in October that the national wave of home foreclosures should be allowed to “run its course and hit the bottom” in order to help the housing industry recover.

Turning to foreign policy, Biden called Romney’s comment on Russia “incredibly revealing.”

“He acts like he thinks the Cold War’s still on,” Biden said, noting Russia’s cooperation with the United States in recent years on Afghanistan and Iran. “This is not 1956.”

Clinton made a similar point. “I think it’s somewhat dated to be looking backwards instead of being realistic about where we agree, where we don’t agree,” she told CNN in an interview.

In Milwaukee, Romney did not mention the administration’s attacks, even as he delivered his standard indictment of the president’s economic stewardship.

Romney spokeswoman Andrea Saul released a statement saying Biden had “demonstrated just how ‘out of touch’ the Obama administration is with reality.”

“After three years of record unemployment and skyrocketing gas prices, the only thing President Obama has delivered is a string of broken promises that have decimated the middle class,” she said.

michael.finnegan@latimes.com