NEW YORK (AP) He claimed she would raise taxes and accused her of supporting open border policies that would allow an influx of unvetted migrants into the country. He blamed her for a litany of the current administrations failures and cast her potential presidency as four more years of the same.

Donald Trump wasnt facing Vice President Kamala Harris . It was Hillary Clinton on the debate stage.

As Trump and Harris prepare to debate for the first and potentially only time Tuesday, his three meetings with Clinton in 2016 illustrate the challenges facing both candidates in what is again shaping up to be an extremely close election.

Harris will face a skilled and experienced debater who excels at rattling his rivals with a barrage of insults and interruptions, while projecting unflappable confidence and conviction. And Trump will be up against a longtime prosecutor known for landing pointed punches. He again faces a woman who would become the countrys first female president, and must contend with the underlying gender dynamics at play.

Trump started out on good behavior

During their first 2016 debate in late September, moderated by NBCs Lester Holt, Trump began on his best behavior. He and Clinton warmly shook hands after taking the stage and Trump, in his first answer, said he agreed with his rival when it came to the importance of affordable child care.

After referring to the former first lady, senator, and secretary of state as Secretary Clinton, he checked to make sure she approved.

Yes? Is that ok? Good. I want you to be very happy. Its very important to me, he said, drawing laughs from the audience and Clinton herself. (In later debates, he called her Hillary, while she consistently used Donald.)

It was Clinton who took the first digs of the night when she criticized the then-reality TV star and real estate developer for supporting Trumped-up trickle-down economics and said their different perspectives were borne from the fact that Trump had received millions of dollars from his wealthy father , while hers had worked hard printing draperies.

In the audience, she said, was a worker who accused Trump of stiffing him on bills.

As the debate wore on, Trump became more combative as he pressed Clinton on why she hadnt done the things she was proposing as a candidate for president during her decades of public life.

Typical politician: All talk, no action. Sounds good, doesnt work. Never gonna happen, he said.

Clintons strategy: laugh it off

Clintons strategy in responding to Trumps attacks was clear from the beginning: Dont get rattled. Laugh it off.

She never appeared flustered and instead smiled widely as she dismissively brushed off what she at one point cast as Trump saying more crazy things.

No wonder youve been fighting ISIS your entire adult life, Trump quipped at one point as he tried to cast Clinton as an all talk, no action politician, of the group that formed in 2013.

I have a feeling that by the end of this evening, Im going to be blamed for everything thats ever happened, Clinton responded with a smile.

Why not? Trump answered.

Trump, meanwhile, sought to turn the arguments she made against him back onto her.

I have much better judgment than she has. I also have a much better temperament than she has, he declared. I think my strongest asset maybe by far is my temperament. I have a winning temperament.

You ought to be ashamed of yourself

The second debate between Trump and Clinton was far more combative. The town hall came just two days after the release of the Access Hollywood tape in which Trump bragged about sexually assaulting women.

With his campaign in freefall and top Republicans urging him to leave the race, Trump invited women who had accused former President Bill Clinton , Hillary Clintons husband, of sexual misconduct, creating a spectacle as the women sat in the audience in the debate hall and spoke at a press conference beforehand.

There was no handshake this time, and the debate quickly devolved into accusations as Trump insisted what former president Clinton had done was far worse than his self-described locker room talk.

Bill Clinton was abusive to women. Hillary Clinton attacked those same women and attacked them viciously, he said. I think its disgraceful, and I think she should be ashamed of herself.

Later, Trump zeroed in on the thousands of hacked emails that Wikileaks had begun to publish the day of the tapes release, as well as Clintons use of a personal email server during her time as secretary of state.

As Clinton sat on her stool, Trump approached her, and said that, if he won, he would instruct his attorney general to hire a special prosecutor to investigate her conduct.

There has never been so many lies, so much deception, he said. There has never been anything like this. ... Lives have been destroyed for doing 1/5th of what youve done, and its a disgrace.

Clinton, again refusing to be flustered, directed viewers to her website where she said her campaign had fact-checked his false allegations.

Its just awfully good that someone with the temperament of Donald Trump is not in charge of the law in our country, she said.

Because youd be in jail, Trump responded to cheers from the audience.

Trump lurked behind Clinton

Beyond encapsulating the sheer nastiness of the race, the debate, which was co-moderated by ABCs Martha Raddatz and CNN s Anderson Cooper , also underscored the gender dynamics at play. Trump, who is physically far larger, lurked behind Clinton at times.

As she apologized for using a private email server, Trump loomed ominously behind Clinton.

During a subsequent question on the Affordable Care Act and rising healthcare costs, Trump stood right behind Clinton as she stepped forward to respond to the audience member who had asked the question. The scene was immortalized in endless memes and parodies and has often been cited as a cautionary tale for male candidates debating women.

This is not okay, I thought, Clinton later wrote in a memoir recounting the episode. She said that, on the small stage, no matter where I walked, he followed me closely, staring at me, making faces. It was incredibly uncomfortable. He was literally breathing down my neck. My skin crawled.

It was one of those moments where you wish you could hit pause and ask everyone watching: Well, what would you do? Do you stay calm, keep smiling, and carry on as if he werent repeatedly invading your space? Or do you turn, look him in the eye, and say loudly and clearly, Back up, you creep, get away from me, I know you love to intimidate women but you cant intimidate me, so back up.

I chose option A, she said, aided by a lifetime of dealing with difficult men trying to throw me off.

I wonder, though, she went on, whether I have chosen option B. It certainly would have been better TV.

No puppet. Youre the puppet

By the third debate, which was moderated by Fox News Chris Wallace, allegations of Russian election interference were dominating the news.

Weve never had a foreign government trying to interfere in our election, Clinton said, expressing outrage that Trump had encouraged espionage against Americans and accusing him of touting the line of Russian President Vladimir Putin in exchange for assistance.

She has no idea whether its Russia, China or anybody else. She has no idea, Trump retorted, contradicting the conclusions of a long list of American intelligence agencies. He insisted he didnt know Putin, whom he derisively said had no respect for Clinton.

Well thats because hed rather have a puppet as president of the United States, Clinton responded.

No puppet, no puppet. Youre the puppet, Trump shot back.

(Trump later said he condemned election interference by Russia or anybody else.)

Clinton, in an interview with The New York Times , referenced the puppet moment as an example of what she hoped Harris would do on stage Tuesday night.

She just should not be baited. She should bait him. He can be rattled. He doesnt know how to respond to substantive, direct attacks, she told the outlet. I mean, when I said he was a Russian puppet and he just sputtered onstage, I think thats an example of how you get out a fact about him that really unnerves him.

Taking advantage of the split screen

But the debate also provided a clear illustration of why Trump is such an effective debater. While Clinton tried to remain above the fray and laugh off attacks, Trump appeared in control, frequently interrupting with quips and commentary.

He also took advantage of the split-screen that kept the camera on both of the candidates faces through much of the debate, often looking straight ahead, projecting strength, and visibly reacting.

When Clinton at one point spoke about her experience, he interjected: Give me a break.

Wrong, he retorted, after she accused him of having mimicked a disabled reporter.

Wrong, he said again after she noted his past support for the invasion of Iraq.

Repeatedly, he tried to direct the proceedings, complementing Wallace or offering direction. After being asked about allegations of sexual assault by a long list of women, Trump insisted the stories were nothing but lies and fiction and then tried to deflect by pivoting to Clintons emails.

What isnt fictionalized is her emails, he said. Thats really what you should be talking about. Not fiction.

Later, Clinton took a swipe at Trump as she discussed her plan to raise taxes on the rich to keep Social Security solvent.

My Social Security payroll contribution will go up, as will Donalds, assuming he cant figure out how to get out of it, she said.

Such a nasty woman, he said, shaking his head.

Time is a flat circle

The debates also demonstrated how little has changed over the last eight years.

During the third debate, Trump was asked for a second time about his efforts to sow doubts about the integrity of the election and claims that it was being rigged. Would he commit to accepting the results, he was asked?

I will look at it at the time, he said, complaining that a dishonest media was working to poison the minds of the voters and claiming, falsely, that millions of people were registered to vote who shouldnt have been.

He also took issue with Clintons candidacy, as he has with Harris after she replaced Biden as the Democratic nominee.

She shouldnt be allowed to run. Shes guilty of a very, very serious crime, he said.

He was asked again whether he would commit to a peaceful transition of power.

What Im saying is that I will tell you at the time, he responded. Ill keep you in suspense.

Clinton called his answer horrifying and noted that anytime anything is not going in Trumps favor from that years Iowa caucuses to losing at the Emmy Awards he alleges it is rigged.

Should have gotten it, Trump said, drawing laughs.

That is not the way our democracy works, Clinton insisted.