By Steve Holland

WASHINGTON (Reuters) - Tempers flared anew between the warring camps of Republican presidential candidates Mitt Romney and Rick Perry based on dueling videos, a sign of their deep-seated antipathy toward each other.

The tensions are reflective of the competing candidacies of two starkly different politicians: Romney the wealthy former governor of Massachusetts and former business executive, and Perry the confident Texas governor with a swagger.

As evidenced by their finger-pointing confrontation at a Las Vegas debate on Tuesday, there are no warm feelings between the two. They talked over each other and when Romney put his hand on Perry's shoulder during one tense exchange, Perry glared in anger at his opponent.

The Romney campaign released a video late on Wednesday entitled "Ready to Lead?"

It includes Perry comments from debates when he appears to be struggling to string a sentence together.

In return, the Perry side launched a video called "Misleading" that criticizes Romney for his record on healthcare and for letting illegal immigrants mow his lawn.

Romney's development of a healthcare system for Massachusetts has been cited by President Barack Obama as a model for his U.S. overhaul, which conservatives want to repeal.

The Perry video, using past comments from Romney himself, suggests Romney has previously liked the idea of having the Massachusetts healthcare replicated throughout the country, but now is against the idea since conservatives oppose what they call "Obamacare."

The video battle is proof that Romney sees Perry as his main threat to the 2012 Republican presidential nomination, and that Perry sees Romney as his key obstacle to making a comeback after losing the front-runner position.

NO ATTENTION TO CAIN

Neither campaign has focused on businessman Herman Cain, the upstart Republican who has steadily gained ground in recent weeks and leads some polls of Republican voters.

Romney and Perry have raised the most money for their campaigns, making them able to fully fund a campaign organization that can last through the key states which hold the early nominating contests in January.

The bare-knuckled nature of the Romney-Perry competition has raised eyebrows but Republican experts say it is not unusual and is in fact healthy.

"This isn't an Oxford debating society," said Republican strategist Rich Galen. "These people are running for president of the United States. You've got to be able to stand up for yourself and knock the other guy down a little bit."

Romney told KSCJ Radio in Iowa that the tough nature of the campaign "goes with the territory."

"I think the people in our party want to make sure that the person we nominate is someone who can beat Barack Obama and can go toe-to-toe with him in debates," he said.

Perry, in a barely disguised jab at Romney in Las Vegas on Wednesday, a day after their debate, said he was the true conservative in the 2012 race.

"I am not the candidate of the establishment," Perry said. "You won't hear a lot of shape-shifting nuance from me. I'm going to give the American people a huge, big old helping of unbridled truth."

(Editing by Mohammad Zargham)