Donald Trump refused to say he would concede a loss to Hillary Clinton in next month's election, adding to concerns that he doesn't respect a central principle of U.S. democracy.

His remarks came near the end of the final presidential debate, when moderator Chris Wallace pressed the real estate magnate and Republican nominee to explain his claims that the election will be "rigged," and whether he would abide by the result.

"I will tell you at the time," Trump said. "I will keep you in suspense."

The Art of the Deal author came into the debate held at the University of Nevada Las Vegas needing to turn the election narrative around, and on that front, he may not have succeeded. Rather than Trump, it was Clinton who appeared more prepared to close the deal of Election 2016.

Clinton, who criticized Trump throughout the debate for his apparent sympathy to Russian president Vladimir Putin, cited her former opponent Bernie Sanders in calling Trump a dangerous person to let near the presidency.

"It's funny but it's also really troubling," Clinton said about Trump's refusal to say whether he would accept the election results. "He is denigrating, talking down our democracy. I am appalled."

Clinton, dressed in a white pantsuit, was better able to articulate her vision of a future America, saying she supports abortion rights, Planned Parenthood, and the right of a woman to make her own decisions about her own health.

Trump claimed Clinton supported conditions where one can "take a baby and rip the baby out of the womb of the mother" even in the ninth month of pregnancy.

"Donald thinks belittling women makes him bigger," said the former First Lady, who referred to Trump by his first name throughout the debate.

Trump has been dogged by accusations that he sexually assaults women, and he said that several who have recently made those charges are liars and doing it for fame. Though his vice presidential running mate and his daughter have both said he apologized for remarks on "Access Hollywood" in 2005, he denied that tonight.

"I didn't even apologize to my wife, who is sitting right here, because I didn't do anything," he said.

Melania Trump herself went on television this week to say he had apologized, and that she forgave him.

"So we now know what Donald thinks and what he says, and how he acts towards women. That's who Donald is," said Clinton. "It's up to all of us to demonstrate who we are and who our country is."

On immigration issues, Trump again promised to build a wall at the Mexican border, saying there are "bad hombres" in the U.S.'s southern neighbor. Clinton responded by citing a Las Vegas girl who worries that her illegal immigrant parents will be deported, and added that when Trump made a trip to Mexico in August, "he choked" because he couldn't bring up the matter of who would pay for the wall, which Mexico has said it will not.

Also pressed by Wallace to say that, along with numerous national security experts, Russian government actors are trying to influence the election by hacking in the emails of Clinton campaign chairman John Podesta, Trump refused. He did cite a number for the amount of nuclear missiles Russia has.

Putin "said nice things about me. If we got along well that would be good," Trump said. "He has no respect for her. He has no respect for our president."

Clinton said that Trump encourages Russian espionage and issues such as the breakup of the North Atlantic Treaty Organization.

Putin wants Trump to win because "he'd rather have a puppet as president of the United States," Clinton said. Trump said Clinton was the puppet.

Trump repeatedly described the situation in the U.S. as terrible and horrible, citing a depleted military, the disrespect of police and the disaster in inner cities, where there are no jobs and no education.

Clinton used her closing remarks to reach out to Republicans and independents as well as Democrats, and she emphasized her focus on children and families. Trump used his to attack her.

A CNN/ORC snap poll following the debate found 52% of viewers said Clinton won the debate, while 39% said Trump came out ahead. The former secretary of state has come out ahead in all three of the network's post-debate polls, though Wednesday marked her smallest margin.

She appeared satisfied with her performance. At the end of their last debate, Hillary Clinton wore a wide grin. Donald Trump scowled.