At the end of the Republican presidential debate in New Hampshire this month, when the Democrats joined the candidates on stage, Mitt Romney found himself momentarily alone as his counterparts mingled, looking around a bit stiffly for a companion.
The moment was emblematic of a broader reality that has helped shape the Republican contest and could take center stage again on Thursday at a debate in Florida. Within the small circle of contenders, Mr. Romney has become the most disliked.
With so much attention recently on the sniping between Senators Hillary Rodham Clinton and Barack Obama on the Democratic side, the almost visceral scorn directed at Mr. Romney by his rivals has been overshadowed.
'Wrestling match with a pig'
“Never get into a wrestling match with a pig,” Senator John McCain said in New Hampshire this month after reporters asked him about Mr. Romney. “You both get dirty, and the pig likes it.”
Mike Huckabee’s pugilistic campaign chairman, Ed Rollins, appeared to stop just short of threatening Mr. Romney with physical violence at one point.
“What I have to do is make sure that my anger with a guy like Romney, whose teeth I want to knock out, doesn’t get in the way of my thought process,” Mr. Rollins said.
Campaign insiders and outside strategists point to several factors driving the ill will, most notably, Mr. Romney’s attacks on opponents in television commercials, the perception of him as an ideological panderer and resentment about his seemingly unlimited resources as others have struggled to raise cash.
Mr. Romney’s campaign contends that the hostility is driven by the fact that he has aggressively sought to win the early primaries, setting himself up as the chief antagonist, first, to Mr. Huckabee in Iowa and then to Mr. McCain in New Hampshire.
Mr. Romney continues to be a mountain in the paths of both men, as well as Rudolph W. Giuliani, to the nomination.
A spokesman for the Romney campaign, Kevin Madden, said, “I think it’s largely driven by the fact that everybody’s taught to tackle the guy on the field with the ball.”
But the New Hampshire debate was striking in that it amounted to a gang tackle of Mr. Romney, even though Mr. McCain was leading in polls in the state.
“The glee the other candidates go after Romney with is really unique,” said Dan Schnur, a Republican strategist who worked on Mr. McCain’s presidential campaign bid in 2000 but is not affiliated with any campaign now.
A senior adviser to Mr. Romney, Ronald C. Kaufman, pointed to his vast personal fortune and upstart status in the political world as breeding resentment.
“They think he didn’t pay his dues,” said Mr. Kaufman, who argued that Mr. Romney had done so by working tirelessly in his campaign.
In stark contrast to Mr. Romney, Mr. McCain seems to be universally liked and respected by the other Republican contenders, even if they disagree with him.
Mr. Schnur used a schoolyard analogy to compare Mr. Romney, the ever-proper Harvard Law School and Business School graduate, to Mr. McCain, the gregarious rebel who racked up demerits and friends at the Naval Academy.
“John McCain and his friends used to beat up Mitt Romney at recess,” Mr. Schnur said.
Although Mr. McCain has now started to draw some cautious challenges from Mr. Giuliani in Florida, he has a longstanding friendship with him, dating from 1998, when they first met.
Mr. McCain also seems to have fallen into a mutual nonaggression pact with Mr. Huckabee, who has been almost fawning in his compliments for Mr. McCain and dripping with contempt when discussing Mr. Romney.
Mr. McCain has drawn criticism as being excessively personal in striking back at Mr. Romney. So he has tried to play down any notion that he harbors special animosity toward him, saying he simply does not know him well.
'Doesn't play by the same rules'
But Mr. McCain’s advisers, whose distaste for Mr. Romney is vivid, say Mr. McCain has been irked by what they perceive as misleading attacks and Mr. Romney’s willingness to say anything to be elected.
“He doesn’t play by the same rules the rest of us do,” said Charlie Black, a senior McCain strategist.
McCain aides were positively gleeful last week as they watched replays aboard their campaign bus of a heated back and forth between Mr. Romney and an Associated Press reporter who challenged an assertion about the influence of lobbyists in his campaign.
Nevertheless, before he criticizes rivals, Mr. Romney often pauses to say that the man is a “friend,” and he seems to believe it.
Mr. Giuliani endorsed Mr. Romney in his race for Massachusetts governor in 2002 and campaigned for him. Mr. Romney got to know Mr. McCain while running the 2002 Winter Olympic Games and went to Washington to seek federal money.
Mr. Romney probably knows Mr. Huckabee the best, aides said, as the two were governors at the same time and ran into each other often through the Republican Governors Association and the National Governors Association.
Paradoxically, sometimes the enmity between them appears to be the sharpest.
Aides to Mr. Huckabee say he did not get to know Mr. Romney very well as a governor, finding him distant at meetings. The aides said they were also irritated that Mr. Romney did not call after Mr. Huckabee’s victory in Iowa.
Mr. Romney shrugged off any tension with his rivals when asked about it.
“You know,” he said, “in this process, people have a real battle for success. But I consider these guys friends.”