From taking a jab at Rosie O'Donnell to consoling Sen. Rand Paul on a difficult night, here are Donald Trump's memorable lines from his first GOP presidential debate. (Fox News Channel)

From the first moment of Thursday night’s Republican presidential debate, Donald Trump showed that he won’t be playing by anybody’s rules but his own.

He refused to say he would support the eventual Republican nominee, bragging about the “leverage” he gains by threatening to run as an independent.

He joked about Rosie O’Donnell. He said he would be justified in being mean to Fox News moderator Megyn Kelly. And he described America’s political leaders as “stupid.”

“I don’t, frankly, have time for total political correctness,” Trump said, drawing cheers. “What I say is what I say.”

Trump’s performance under the bright lights here at the Quicken Loans Arena revealed a politically raw novice but also a natural entertainer whose skills as a high-rolling business magnate and reality television star prepared him for this summer turn. For those who have seen his bombast as a potential danger to the party — or to his own ability to be seen as a viable candidate — his sometimes meandering answers and awkward interactions provided fodder for more skepticism.

Time and again, Trump, whose place atop the polls put him at the center lectern, reveled in sharing his snappy views and sharp-edged personality while his rivals on stage treated him carefully or with disdainful lines that riled but never quite punctured.

He seemed to position himself in an unusual way, as a blunt truth-teller who is willing to blow up the established order but also a consummate insider who has donated millions of dollars to politicians in both parties, including some of his current competitors.

He even pointed to his own donations, and the favors that politicians have done for him in return, as an example of what’s wrong.

“When they call, I give,” he said. “They are there for me, and that’s a broken system.”

He jabbed at some of his nearby hopefuls, at one point telling Sen. Rand Paul (Ky.), “You’re having a hard time tonight.” (Paul wears a hearing aid.)

Trump asserted that his incendiary comments on illegal immigrants have revived the debate on border security rather than damaged the Republican brand. “If it weren’t for me, you wouldn’t even be talking about illegal immigration,” he said. “This is not a subject that was on anyone’s minds.”

The scene, which was expected to draw record viewership for a primary debate largely because of Trump’s presence, underscored two major developments this summer in the roiling battle for the Republican nomination. For his part, Trump showed a longing to be seen as more than a rambling billionaire as well as some increased discipline since his June launch. His adversaries, meanwhile, acknowledged with their words and manner that, in a time of sprawling conservative unrest, Trump has become a force who is instinctively channeling the base’s frustrations.

“Donald Trump is hitting a nerve in this country,” said Ohio Gov. John Kasich. He added: “For people who want to just tune him out, they’re making a mistake.”

Another rival, former Silicon Valley executive Carly Fiorina, said in an earlier debate among the lower-tier candidates that Trump has “tapped into an anger that people feel.”

Still, Trump demonstrated that he is often balancing precariously between the everyman outrage he claims to represent and a sharp-tongued pomposity that could rattle his candidacy with a single sentence.

Occasionally, his one-liners drew boos and jeers from the audience. When the crowd moaned after Kelly noted his past support for abortion rights and asked when he became a Republican, Trump conceded: “I don’t think they like me very much.”

At another point, Trump bragged about having his businesses declare bankruptcy four times. Rather than feel shame about publicly acknowledging these failures — and leaving his lenders in the lurch — Trump portrayed his actions as a savvy manipulation of the laws passed by the typical politicians standing next to him. He blamed the media for tut-tutting about it because they are obsessed with “Trump, Trump, Trump.”

On his rough experience in struggling Atlantic City, Trump took aim at New Jersey Gov. Chris Christie. “Chris can tell you” all about the seaside city’s economic downturn, Trump said.

“I had the good sense and I’ve gotten a lot of credit in the financial pages, seven years ago I left Atlantic City before it totally cratered,” Trump said. “I made a lot of money in Atlantic City, and I’m very proud of it.”

Trump’s decision to decline to rule out an independent bid was startling for its candor — “I fully understand” the question, Trump repeated — and for Trump’s insistence on not bowing to pressure to get in line and become a Republican loyalist.

As ever, Trump slammed the political press, a favorite foil, calling reporters a “dishonest lot” who did not understand his corporate empire or his political positioning.

In one exchange of the type that would cause a normal politician to cower — and likely bury his campaign — Kelly asked Trump about numerous insulting and disparaging statements he had made about women. Trump was not bothered in the least about this line of questioning. In fact, he encouraged it.

“You’ve called women you don’t like ‘fat pigs, dogs, slobs, and disgusting animals,’ ” Kelly said.

“Only Rosie O’Donnell,” replied Trump, drawing laughter from the crowd.

“For the record, it was well beyond Rosie O’Donnell,” Kelly persisted.

“Yes, I’m sure it was,” Trump agreed, drawing more laughs.

Trump offered a few kind words for former Florida governor Jeb Bush, calling him a “gentleman.” But when Bush expressed concern about Trump’s immigration rhetoric, saying the GOP should offer a more hopeful message, Trump responded that, in a hostile world, “we don’t have time for tone.”

Trump resisted taking the bait when he was egged on by Fox News’s Chris Wallace to knock Bush on immigration. Instead, Trump delved into the reasons to “build a wall.” Only near the end did he mention Bush: “We need, Jeb, to build a wall. . . . We need to keep illegals out.” Bush stayed silent.

In closing, Trump returned to how he began, his face solemn. “We don’t win anymore,” he said, listing countries that he believes are outpacing the United States. Unlike the others’ closings, it wasn’t a biographical note; it was a feeling, and it was entirely Trump.