WASHINGTON — Republican activists foresee a long, lumbering presidential campaign that almost certainly will nominate Mitt Romney but may leave him weakened in a fall battle against President Barrack Obama.

Interviews Wednesday with GOP officials and strategists in several states found no panic or calls for Romney to crank up his criticisms of Rick Santorum to secure the nomination. But they expressed varying degrees of worry that Santorum’s and Newt Gingrich’s attacks on Romney are inflicting wounds that might not fully heal by Nov. 6.

“The shelf life is 48 hours for a lot of this,” including small-bore disputes over policy differences, said Steve Lombardo, a veteran of many GOP campaigns.

“The bigger concern is the negatives the governor has built up on his unfavorable rating,” Lombardo said, referring to impressions that Romney, the former Massachusetts governor, waffles on key principles and can’t relate to working-class people. “Those can be harder to reverse,” he said, and Romney would like to address them without potshots from his own party.

South Carolina Republican Chairman Chad Connelly is more upbeat. He says Romney won’t suffer from a protracted nominating process.

“A longer, drawn-out primary engages people across the nation,” Connelly said. He said Obama put the Rev. Jeremiah Wright controversy behind him because he dealt with it forcefully in the spring of 2008, months before the general election. The “swiftboat” attacks hit Democratic presidential nominee John Kerry much later in the 2004 election cycle, “and he never recovered,” Connelly said.

But Mike McKenna, a GOP consultant from Richmond, Va., said Romney’s struggles in the primaries and caucuses point to serious problems this fall. Romney won 41 percent of the primary vote in his native state of Michigan to Santorum’s 38 percent, McKenna noted, calling it “hardly a dazzling performance.”

Romney’s margin was even smaller in Ohio, even though he again heavily outspent Santorum. McKenna, who conducts focus groups and polls, sees ominous trends. He predicts that one-fourth to one-third of all Republicans “will not vote for Romney” if he’s the nominee this fall.

Nelson Warfield, an adviser in Bob Dole’s 1996 presidential campaign and Texas Gov. Rick Perry’s recently ended bid, is nearly as gloomy.

“The mathematics of the race are very troubling for Mitt Romney,” Warfield said. “He can’t put this away. The big question for Republicans is: Will his problems go away when he’s the nominee, or will they carry on into the general election?”

John Ullyot, a Republican strategist and former Senate aide, said the long, difficult primary “just weakens Romney in the general election. It saps resources, it keeps him from focusing on President Obama.”

Other Republican campaign veterans are more optimistic, although few predict an easy path for Romney. Rich Galen, a former aide to Gingrich and former Vice President Dan Quayle, said Romney’s hard-hitting TV ads are having less impact than they did a few months ago. Voters now know Gingrich and Santorum much better, Galen said, and they are less shocked by negative information and more willing to draw independent conclusions about the candidates.

Rather than hit Santorum harder, Galen said, Romney should “turn the tables and show how smart he is, how he can do the things he needs to do” to be a good general election candidate and president.

Chris LaCivita, a Virginia-based GOP strategist, said Romney’s steady collection of party delegates makes it almost impossible for Santorum and Gingrich to prevail, and they should step aside for the party’s good.