LA CROSSE, Wis. — Rick Santorum has eased up on using phrases like “worst Republican in the country” when tearing into Mitt Romney. And he is no longer saying that a vote for Mr. Romney would be basically the same thing as a vote for President Obama.


Meet subdued Santorum.


After several highly publicized remarks that left many in his party questioning whether he had crossed the line in attacking a fellow Republican, Mr. Santorum has struggled to find the balance between being a tenacious underdog and leaving himself open to criticism that he is just an embittered also-ran.


He still reserves plenty of derision for Mr. Romney, mocking him repeatedly as the “Etch A Sketch” candidate whose conservative values are malleable and insincere. But in campaign speeches across Wisconsin the past few days he has directed more of that outrage at Mr. Obama, particularly over the issue of government-mandated health care.


He is now refraining from more pointed language. Mr. Romney is “uniquely disqualified,” as Mr. Santorum has mildly put it, to make the argument for conservatives that Mr. Obama’s health care plan should be repealed.


“I’ve got a long, strong, consistent record on the issue of health care,” Mr. Santorum told a group of more than 100 supporters at a campaign rally in Janesville on Tuesday night. “No wobbles, no bobbles.”


The sudden restraint has surprised some of his supporters.


Paul Kurtz, a high school social studies teacher from Janesville who was at the rally, said he thought Mr. Santorum seemed to be repressing his trademark tenacity.


“I think Rick tempered what he could have said,” said Mr. Kurtz, 36, who was sipping the dregs of a beer as the crowd filed out of the Armory in Janesville. “I think he was really close to going there. I was waiting for the personal attack on Romney.” But Mr. Kurtz left disappointed.


Underlining the dilemma Mr. Santorum faces as he tones down — temporarily, at least — some of his sharper words, Mr. Kurtz said he understood the need to be so brusque.


“I’ve seen 10 Romney ads,” he said. “But I haven’t seen one Santorum ad.”


Given how overwhelmingly he is being outspent by Mr. Romney and his allies — who have so far committed $3 million to advertising compared with about $700,000 from Mr. Santorum and his supporters — Mr. Santorum’s fiery attacks are essentially his most potent campaign weapon. Milquetoast sound bites do not suffice for the kind of national media attention his campaign thrives on.


And his fervor is one of the characteristics his supporters find most appealing.


“We all wish he’d kind of tone it down a little,” said Heather Larson, 26, who works at a day care center in Viroqua, a small city southeast of La Crosse, which sits along the Wisconsin-Minnesota border. “But we understand the passion. And that’s why we support him so much.”


Ms. Larson, along with about a dozen other young Republicans, went to a bowling alley in La Crosse on Wednesday to meet Mr. Santorum, bowl and share pizza with him.


But that passion has been the source of more than one foot-in-mouth moment for Mr. Santorum recently. He raised eyebrows last month when he said that John F. Kennedy’s 1960 speech on the separation of church and state made him want to “throw up.” After initially defending the remark, he later said he regretted it.


Mr. Santorum’s opponents pounced on him a week and a half ago after he said, “I don’t care what the unemployment rate is going to be” while campaigning in Illinois.


Though he made the remark in a broader context — he was saying he viewed his campaign as a fight for freedom and not about any single issue like the economy — he spent the next week explaining himself.


He was also forced last week to explain why he had said “we might as well stay with what we have” when making the argument to a Texas crowd that Mr. Romney’s policies did not offer a clear contrast with Mr. Obama’s. Then on Sunday he uttered a profanity after a reporter for The New York Times asked him to clarify a comment that Mr. Romney was the “worst Republican in the country” to nominate. He said that he was talking only about Mr. Romney’s capacity to lead the Republican Party in a challenge to Mr. Obama’s health care law.


With some polls showing Mr. Romney’s unpopularity on the rise — a new Washington Post survey released on Wednesday showed half of Americans now express unfavorable views of him, a new high for him — some Republican voters question whether Mr. Santorum sometimes plays too rough.


“It alarms me,” said Frank O’Laughlin, 49, a resident of La Crosse who works for the National Guard finding jobs for veterans.


Mr. O’Laughlin, who said he did not know which candidate he would vote for in Tuesday’s primary, visited the bowling alley to make his own assessment of Mr. Santorum.


Both Mr. Romney and Mr. Santorum have been far too negative, Mr. O’Laughlin said.


“We’re going to point fingers and jab and bruise rather than heal,” he said. “And it’s all just a lot of noise.”


At a restaurant on Wednesday in Onalaska, a small city north of La Crosse, Mr. Santorum stood in front of a window with panoramic views of the Mississippi River and a banner bearing the word “Freedom.” A large government role in health care like Mr. Obama supports, he told a crowd of about 100, poses a threat to their personal liberties similar to what colonial Americans faced from the British monarchy.


“You no longer become a people where the government is there to serve you, but you will become a people just like the folks who conducted a revolution back in 1776,” he said.


Toward the end of his speech he reached for his Etch A Sketch, which an aide usually places near his lectern. The toy should remind them, he said, “who is the conviction conservative, and who is someone who, as his own campaign admitted, writes his own policy on an Etch A Sketch.”