LAS VEGAS — On paper, these debates are called presidential. In reality, they have been everything but.
They have featured eye-rolling, smirking, stalking, pointing, grimacing, interrupting. Sexually explicit allegations have been front and center, and substance has been scarce.
Presidential? Maybe if the job in question were president of World Wrestling Entertainment.
But as negative and divisive as these historically contentious face-offs have been, observers — backed up by polls — say they have been the most pivotal in decades in helping voters determine the outcome of a White House contest.
The final encounter Wednesday offers Donald Trump a final chance to salvage his campaign, and tilt the odds back in his favor.
So far, the first two debates have showcased Trump’s weaknesses as a candidate, on live TV, before audiences of tens of millions of Americans.
“They’ve accelerated Donald Trump’s self-destruction. I think that’s clear,” said John Weaver, a longtime Republican strategist and top adviser to John Kasich. “It would be a much closer race probably had there not been any debates.”
“We’ve had three hours of debate. Outside of the first 30 minutes . . . it’s been 2½ hours of unmitigated disaster” for the Republican nominee, he added. “Everyone wondered how he would perform without a Teleprompter. Now we know.”
Hillary Clinton arrives in Las Vegas for the final debate like a poker player holding a full house, confident and careful. Trump is furiously raising his bet, acting as if he’s holding a hot hand, when polls say all he’s got is a pair of jacks.
Trump’s odds of turning around his campaign in the third debate are steep. Thus far, Clinton has deftly walked Trump into traps that revealed his angry, vengeful side.
The Republican nominee has difficulty backing down from a fight, even when it’s in his best interest, and his battles days after the first debate over his shaming of a former Miss Universe took a heavy toll. The second debate did little to put to rest his treatment of women, with new polls showing a further erosion of female support for Trump.
Clinton’s strategy has been to let Trump talk, hanging himself with his own words. The real estate mogul has uttered 25 percent more words than Clinton, according to a Globe analysis of the first two debate transcripts.
“Mr. Trump has given two amazing debate performances, with the second being one of the greatest of all time,” said Hope Hicks, a Trump spokeswoman. “The only weaknesses that were exposed were those of Hillary Clinton.”
Clinton has spent most of the past week without holding public events as she prepares for Wednesday’s 90-minute debate. The event, which airs at 9 p.m. from the University of Nevada Las Vegas, is being moderated by Fox News host Chris Wallace.
She is sure to face questions over the drip-drip-drip of e-mails from her campaign chairman John Podesta, which showed partial transcripts of her speeches to Goldman Sachs as well as a poll-tested candidate whose own campaign struggled at times to define her. Trump is also likely to focus on revelations Monday that a top State Department official had negotiated with the FBI over classification of some of Clinton’s e-mails that were on her private server.
In the first two debates, Trump adopted two approaches.
“Looking back on it, there were two Donald Trumps,” said political historian Douglas Brinkley. “The first debate he was trying to be in the zone of plausibility as a normal type of candidate.
“Because that did not work for him, he said the shackles were being taken off. He decided his best strategy was the nuking of Hillary Clinton,” he added. “The second debate will be among the most memorable in American history for his threat to put her in jail. That is one for the ages and will be marked as one of the most startling moments in the annals of American politics.”
Leading into the first debate, polls signaled that Trump had the momentum in the campaign. Some national polls showed him edging into a slight lead after several bad weeks for Clinton. He was ahead or within striking distance in swing states. Democrats were on edge.
But then toward the end of the first debate, Trump faltered badly when Clinton brought up Alicia Machado, the former Miss Universe from Venezuela whom Trump once ridiculed as overweight.
Trump seemed rattled: “Where did you find this? Where did you find this?” he demanded of Clinton. Trump refused to back down, and continued to defend his description of Machado’s weight in subsequent days.
At the second debate, on Oct. 9 in St. Louis, Trump put on a show. About 90 minutes before the debate was to begin, he held a press event with three women who accused Bill Clinton of sexual abuse in the 1990s. In transforming the debate setting into a reality-TV spectacle, however, he failed to make the point resonate.
Then, in the opening moments of the debate, Trump discussed the women’s allegations as they sat in the audience, with Bill Clinton sitting nearby and Hillary Clinton on stage. It was the most awkward and sordid display in modern presidential debate history.
“I think she should be ashamed of herself, if you want to know the truth,” Trump said of Clinton, claiming she participated in discrediting the women.
Clinton ignored the bait almost entirely and, quoting Michelle Obama, said, “When they go low, we go high.”
Trump later said that, if he is elected, he would direct the Department of Justice to appoint a special prosecutor to investigate Clinton. He said he wanted to put her in jail. To many critics, that sounded more totalitarian than presidential.
The second debate was injected with drama after the Washington Post revealed a 2005 Access Hollywood videotape that captured Trump talking in the most vulgar and obscene terms about sexually assaulting women, and getting his way because of his outsized celebrity honed on TV.
After repeated questioning, Trump said that he never acted the way he spoke — a claim that later triggered more women to come forward and say that he had, despite their protests, groped them or kissed them on the lips upon their first meeting.
Trump has denied all the charges, and claimed that he is the victim of a rigged election.Matt Viser can be reached at firstname.lastname@example.org. Follow him on Twitter @mviser.