Super Tuesday confirmed anew that Mitt Romney remains the favorite to win the Republican presidential nomination, but his slow, unsteady march is coming at a steep price. As he advances toward victory in the primaries, he is losing ground in the general election.

Nomination battles often strengthen the winner, but some take a toll. Rarely is there a straight line between March and November that predicts the outcome of a general election. Still, Romney is in worse shape at this point in the campaign than virtually all recent previous nominees.

Demographically, his image among independent voters, the most critical swing group, is more negative now than it was when the primary battle began. He could be hurt among women. He is in trouble with Latinos, a growing part of the electorate that is tilting even more Democratic than it was four years ago. He is not as strong as he needs to be among working-class white voters, among whom President Obama has been consistently weak.

Geographically, the numbers from several key states have been discouraging for the former Massachusetts governor. Pre-primary polls in Ohio, Virginia and Michigan showed him running behind Obama by low double digits. Ohio is a must-win for the Republican nominee in the fall, and Virginia is a state the GOP is determined to take back from the president. Republicans once thought Michigan would be a possible battleground, but at this point it isn’t.

Karl Rove, the GOP strategist who guided George W. Bush to his presidential victories, said it is far too early to know what effect the nomination fight will have on Romney’s fall prospects, should he become the nominee. “It’s way premature to say it’s dispositive” about the outcome of the general election, he said.

No one on either side is predicting anything but a close contest in November, given the state of the economy and the nation’s partisan divisions. Obama may look stronger in head-to-head matchups with his Republican rivals today than he did a few months ago, but vulnerabilities remain.

Republicans say the president’s weaknesses will appear more significant once their candidates stop pounding one another and focus the full force of the GOP machinery — including their super PACs — on the president. Romney’s allies think he ultimately will be strengthened by the nomination fight, saying his opponents have helped to make him a tougher campaigner and a better debater.

Romney has been squeezed between the demands of winning the nod of a party that is more conservative than it was four years ago and the realities of a general election in which winning the middle is crucial.

The more successful he has been at fending off his GOP rivals, and the longer he has had to fight to prove his conservative bona fides, the more conflicted he is about the need to woo the fall electorate.

“He’s sitting there thinking, ‘This will all dissipate when these other guys get off the stage and stop attacking me,’ ” Democratic pollster Mark Mellman said. “History suggests that’s not likely to happen. Once you reach a plateau, the negatives are hard to shake, absent some dramatic event.”

There are many reasons Romney is in this position. The party’s rules for this primary contest were designed to stretch out the battle, meaning the front-runner cannot wrap things up quickly. Super PACs have helped keep competitors alive longer than they would have been in the past.

The GOP fight has been extremely negative, and super PACs have contributed significantly to the tone of the contest. Former senator Rick Santorum (Pa.) and former House speaker Newt Gingrich (Ga.) have attacked Romney throughout the winter, and their super PACs have done more.

But Romney’s campaign and super PAC have aired more negative ads than the others by far. Some Romney supporters believe the former governor’s image has been damaged as much by the tactics he has used to go after his rivals as by the attacks they have aimed at him.

Beyond the tone of the campaign, Romney has hurt himself with some key constituencies. He accused Gingrich and Texas Gov. Rick Perry of being soft on immigration. That helped dispose of Perry, but it appears to have offended Hispanic voters. A poll by Fox News Latino, released Monday, showed Romney winning just 14 percent of the Hispanic vote in a general election against Obama.

The degree to which the campaign has tarnished the Republican Party was highlighted in a new NBC News-Wall Street Journal poll. Republican pollster Bill McInturff, who conducts the survey with Democratic pollster Peter Hart, was quoted by the two news organizations as saying that the primary season has had a “corrosive” effect on the GOP.

Hart said Romney has two problems. First, a portion of Republicans “can’t stand” the former governor. They represent a fraction of the fall electorate but Romney must have their support to win a close race.

Hart said Romney’s other problem is one of perception, which could be far more difficult to solve. Voters still aren’t sure they know who Romney is, or what his core values are. Nor has he found a way to connect with them. “That’s where he really has a major difficulty,” Hart said. “People look and say this guy just doesn’t relate. It’s a problem with Republicans. It’s a bigger problem with independents.”

Former Republican National Committee chairman Michael S. Steele said Monday on C-SPAN that Romney missed an opportunity last week to reach out to independents by not taking a stronger stand against Rush Limbaugh after the conservative talk show host attacked Georgetown University law student Sandra Fluke as a “slut” and a “prostitute” for her position on health insurance coverage of contraceptives.

Steele said Romney had an opportunity “to look America in the eye and say this is not what conservatism is about, this is not the party that I want to lead, this is not the country I want to lead. . . . Why not begin to make that pitch . . . to independents?”

Kevin Madden, a Romney loyalist and GOP strategist, said current polls are not predictive. He argued that a fall campaign in which the economy is the focus will play to Romney’s strengths. He argued that Romney’s verbal gaffes, which have reinforced his image as a wealthy businessman who is out of touch with ordinary Americans, would fade in the general-election battle.

“When this is a campaign that the governor makes about the voter, about their concerns about the economy, about their aspirations for the future, I think he will have a greater ability to connect with voters,” he said.

A Democratic elected official, who spoke on the condition of anonymity to offer a candid assessment, said he worries that many people in his party are overly confident. “Romney will move back to the middle,” he said, “and I think the race could look very different in September than it does today.”

No doubt that things could change by then. But that depends on how well Romney manages the twin challenges of winning his nomination against stubborn opponents while trying to undo the damage that the struggle has inflicted on him.