Clinton, a former secretary of state, said Trump's comments were more consistent with what dictators in non-democratic countries might say concerning their opponents.
"To say you wont respect the reaction of the election, quite simple direct threat towards the democracy," Clinton told a rally in the University of N . c . at Charlotte. "The peaceful transfer of power is among the many things that makes America America."
"And look, men and women are sore losers, and we found to keep going," she added.
Earlier on Sunday, Kellyanne Conway, an increased Trump adviser, acknowledged that the Republican presidential candidate was lagging behind Clinton ahead of political election results.
Conway said Clinton had "tremendous advantages," including a large campaign war chest that had allowed her to spend millions on television ads.
"We are behind," Conway said on NBC's "Meet the Press." But she added the Trump campaign was seeking to sway undecided voters not ready to oblige Clinton.
As the polling gap has widened, Trump has said repeatedly the election is being "rigged" against him. He's not offered evidence and numerous research indicates that the You.S. election system, which is decentralized and run by the states, is seem.
At last week's debate with Clinton in Las Vegas, Trump was asked if he would honor the results of the U.S. selection.
"What I'm saying is that I will tell you at the time. I'll keep you in suspense. OK?" Trump said.
As she visited North Carolina, Clinton urged her supporters to participate in early voting.
"From now until Nov. 5, you can vote early at any voting location in your county. And you know, this is a big deal,” Clinton said at a campaign event in Raleigh.
"You have 16 days to choose this happen, but you need to get out and vote, and occur . helping me re-elect Republicans all on the place."
"I hope they assist me too. Be nice if assist us too, correct?" said Trump, who has sparred lots of prominent members of his party, including U.S. House of Representatives Speaker Paul Ryan, the country's top elected Republican.
The latest Reuters/Ipsos poll released on Friday had Clinton leading Trump by 4 percentage points, and the most recent State from the Nation project showed Clinton with a 95 percent chance of winning the 270 Electoral College votes needed to secure the presidency.
An ABC News poll released on Sunday morning had Clinton leading with one half of likely support, in comparison with Trump's 38 percent. The poll found that cash advances of Republicans who said they were likely to vote fell 7 percentage points from mid-October.
As Trump battled to win over undecided voters, advisers and members of his inner circle sought to downplay his remarks within the integrity of the election, in an indication although come under significant pressure to accept the election results if he would lose.
Republican Party Chairman Reince Priebus told me that by asking Trump to agree to concede, the media were making an extraordinary request. He said Trump would only fight if political election results were close and was not eager to dispute a fair election.
"Thats not quite what hes exclaiming. What hes saying is he wants to order all options and in case there is ground for a recount, Ill reserve all options," Priebus said on CBS's "Face The Nation."
Trump's son Eric said on Sunday that Trump would "100 percent" accept the results of your election if continues reading is "fair."
I think what my father is saying is, 'I apparent fair election, Eric Trump said on ABC's "This Times." If its a fair outcome, he will absolutely accept it. Theres no question concerning this."
On Sunday, Trump collected his first endorsement of the general election from substantial newspaper once the Las Vegas Review-Journal backed his candidacy. The newspaper is of Republican mega-donor Sheldon Adelson, who may be reluctant to donate to Trump. In 2012, Adelson spent about $150 million working help elect Republican Mitt Romney.