Key moments in the Republican presidential debate
Republican presidential hopefuls Donald Trump (L) next to Jeb Bush during the Republican Presidential Debate at the Ronald Reagan Presidential Library in Simi Valley, California, September 16, 2015 (AFP Photo/Frederic J Brown)

Republican White House hopefuls held their second presidential debate, a charged and at times highly personal political joust. Here are some notable moments:

- Money, money, money -

"I say not in a braggadocious way, I've made billions and billions of dollars dealing with people all over the world."

Donald Trump lays on his characteristic bombast from the outset.

- Getting personal -

"She's absolutely the love of my life, and right here, and why don't you apologize to her right now."

Former Florida governor Jeb Bush demands an apology from Trump for the suggestion he is soft on immigration because he has a Mexican-American wife, who was in the audience.

- School yard fights -

"His visceral response to attack people on their appearance, short, tall, fat, ugly, my goodness, that happened in junior high. Are we not way above that?"

Senator Rand Paul takes issue with Trump's personal insults on the campaign trail.

"I never attacked him on look, and believe me, there is plenty of subject matter there."

Trump shows gives no quarter in response.

- They heard -

"I think women all over this country heard very clearly what Mr. Trump said."

Former Hewlett-Packard CEO Carly Fiorina addresses Trump's comments about her face.

- Graphic -

"A fully formed fetus on the table, its heart beating, its legs kicking while someone says we have to keep it alive to harvest its brain. This is about the character of our nation."

Fiorina gets rapt applause for an impassioned attack on Planned Parenthood -- government-funded reproductive health clinics that have become a lightning rod for conservatives because they also provide abortions.

- Corporate takeover -

"I'm (as) entertained as anyone by this personal back and forth about the history of Donald and Carly's career, for the 55-year-old construction worker who doesn't have a job, who doesn't have money to fund his child's education, I gotta tell you the truth. They could care less about your careers. They care about theirs."

New Jersey Governor Chris Christie is unimpressed by a back-and-forth between the campaign's two CEOs on their business record.

- Brotherly love -

"As it relates to my brother, there is one thing I know for sure, he kept us safe."

Bush raises eyebrows by coming in defense of his brother, who was president during 9/11 and the Iraq War.

- Does your Mom know, Jeb? -

"Forty years ago I smoked marijuana... I'm sure other people did it and didn't want to admit it in front of 40 million people... My mom’s not happy that I just did."

Bush comes clean on his pot use.

- Hitting Hillary -

"I, too, have traveled hundreds of thousands of miles around the globe but unlike Mrs. Clinton, I know flying is an activity, not an accomplishment."

Fiorina offers a curt dismissal of Clinton's frequent travel as secretary of state.

- Code name -

Each candidate was asked what they would choose as their Secret Service code name. Christie opted for "True Heart," John Kasich for "Unit Two" (his wife was unit one), secretary-turned-CEO Fiorina went with "Secretariat", Scott Walker chose "I love riding Harleys."

Bush tried a drop of self-deprecation with "Ever ready," joking at Trump's criticisms about the tempo of his campaign. "Very high energy, Donald," he quipped.

The real estate mogul opted for "Humble," raising laughs, Ben Carson ("One Nation"), Cruz ("Cohiba"), Floridian Marco Rubio ("Gator"), Mike Huckabee ("Duck Hunter"), Paul ("Justice never sleeps") -- which the moderator noted was a mouthful.