Setting a combative tone from the start, billionaire businessman Donald Trump took the spotlight in the first Republican presidential debate, declaring he would not commit to supporting the party's eventual nominee and would not rule out running as a third-party candidate.
"I will not make the pledge at this time," Trump said. He also refused to apologize for making insulting comments about women, saying, "The big problem this country has is being politically correct."
Kentucky Sen. Rand Paul immediately jumped in to challenge Trump on his refusal to commit to supporting the party nominee.
"He's already hedging his bets because he's used to buying politicians," Paul said.
Trump's blunt style was in line with the approach he's taken to his campaign throughout the summer, appealing to voters frustrated with career politicians and perplexing his rivals. He entered the first debate leading the polls in a field filled with governors and senators.
Most of the candidates on stage avoided engaging directly with Trump in the debate's early moments. While 17 Republicans are seeking the party's nomination, only 10 were invited by debate host Fox News to participate in the main event based on their showing in recent polls.
Former Florida Gov. Jeb Bush, a favorite of the party's establishment wing, defended his call for a path to legal status for people living in the U.S. illegally. It's an unpopular position among some Republican voters who equate legal status with amnesty.
"The great majority of people coming here have no other option," Bush said.
Trump in particular has pushed the issue of immigration throughout the summer, drawing criticism for saying Mexican immigrants are rapists. He said Thursday that he had been told that by border patrol agents, and he took credit for immigration being an issue in the2016 campaign.
"If it weren't for me, you wouldn't even be talking about illegal immigration," he said.
To Trump's right on the stage was Wisconsin Gov. Scott Walker, whose victories over unions in his home state created his national profile. Florida Sen. Marco Rubio, the youngest candidate in the field at age 44, is trying to carve out a niche as a foreign policy authority, but has struggled to break through this summer — particularly since Trump's surge.
Also on stage: A lineup of candidates with sharply conservative records and attention-grabbing personalities seeking to pull the party further to the right, including Texas Sen. Ted Cruz, surgeon and tea party favorite Ben Carson and former Arkansas Gov. Mike Huckabee, a popular choice among evangelicals and social conservatives. Kentucky Sen. Paul adds a libertarian twist to the Republican field.
Rounding out the top 10 are two governors. New Jersey's Chris Christie is a past favorite looking to return to the top tier, while Ohio's John Kasich is a latecomer to the race whose first campaign for president 16 years ago never took off.
The remaining seven were relegated to a pre-debate forum, a low-key event in a largely empty arena, where candidates avoided debating each other and largely stuck to scripted responses on domestic and foreign policy.
Former Texas Gov. Rick Perry and businesswoman Carly Fiorina opened the early event with biting criticisms of Trump.
Perry — whose failed 2012 White House campaign was damaged by an embarrassing debate stumble — accused Trump of using "his celebrity rather than his conservatism" to fuel his run for president.
Fiorina, the only woman in the GOP field, said that Trump had tapped into Americans' anger with Washington, but she challenged the businessman as lacking policy positions. "What are the principles by which he would govern?" she asked.
While the candidates pitch their visions for the Republican Party's future, they'll also be making the case that they would present the strongest general election challenge to Hillary Rodham Clinton, the front-runner for the Democratic nomination.
Clinton was scheduled to be traveling during the debate and didn't plan to make a statement afterward. Her campaign preemptively made the case that there was little difference between Trump's "outrageous" positions and the rest of the field.
"They all have an identical agenda," said Joel Benenson, Clinton's chief strategist.
Thursday's debate is the first of six party-sanctioned forums scheduled before primary voting begins in February. Fox News used national polls to determine which 10 candidates would be on the stage, and several candidates were grouped together in the single digits — most separated by a number smaller than the polls' margin of error.