Republican presidential candidate businessman Donald Trump speaks during the CNN Republican presidential debate.

Republican Party front-runner Donald Trump began the party’s second presidential debate with a bang, throwing his well-practiced barbs in all directions, but was quiet for long stretches as 10 fellow candidates for the 2016 presidential nomination bore down on serious issues.

Standing at center stage, Trump – still a long-shot candidate for the White House – declared that he had a “phenomenal temperament” and a record in business that would help him on the world stage. The temperament of Trump, who has made a series of incendiary comments about women and Hispanic immigrants, was again up for discussion during Wednesday night’s marathon debate.

Trump’s unexpected rise and surprising durability is seen as a reflection of voters’ frustration with Washington and career politicians. He drew a heavy challenge from another Washington outsider with a business background: former Hewlett-Packard CEO Carly Fiorina, the only Republican woman in the race.

Fiorina earned praise for her debut performance in the party’s main debate, commanding the three-hour event’s first half – when the television audience was likely the most engaged. Trump has become increasingly critical of Fiorina as her standing has risen.

Fiorina drew the night’s first loud ovation when asked about Trump’s earlier denigration of her looks; he later denied he was referring to her appearance.

“I think women all over this country heard very clearly what Mr. Trump said,” Fiorina said.

Trump retorted: “She’s got a beautiful face, and she’s a beautiful woman.”

The billionaire businessman has invited scrutiny with remarks that would have undone a more traditional candidate. Trump’s climb to the top of the field has unnerved Republican leaders who fear the former reality TV star is damaging the party’s brand and imperiling its chances of winning back the White House after President Barack Obama’s eight-year tenure ends.

Trump has so far been immune to criticism for his lack of specific policy proposals, his caustic rhetoric and his uneven support of conservative principles. And he’s been unpredictable, as he was in the first moments of the debate: unprompted, Trump declared that fellow 2016 presidential candidate Rand Paul shouldn’t even be on the stage.