The biggest moments from Kamala Harris and Donald Trump's first — and maybe only — debate

• Kamala Harris and Donald Trump are debating for the first — and maybe only — time in Philadelphia.
• It's the highest-stakes moment of the presidential campaign yet.
• Here are the biggest takeaways from the debate so far.

Vice President Kamala Harris and former President Donald Trump met for their first debate on Tuesday night.

The high-stakes face-off, taking place at the National Constitution Center in Philadelphia, may be the two candidates' only debate of the election — they have not yet agreed to meet for a second time.

Here are the biggest takeaways from the debate so far.

Kamala Harris made a point to shake hands with Trump

For the first time since 2016, the two presidential candidates shook hands on the debate stage.

It was Harris who made the first move, crossing the stage toward Trump to greet him at the outside of the debate.

"Kamala Harris, good to debate with you," the vice president could be heard saying.

Harris often sneered at Trump as he spoke

Despite the Harris campaign's best efforts, each candidate's microphone remained muted while the other was speaking. But that doesn't mean that the Vice President didn't communicate with viewers as Trump spoke.

Harris could often be seen on the split-screen staring over toward Trump with a bewildered look, narrowing her eyes and shaking her head at times. When Trump dubbed her a Marxist, she even appeared to laugh, placing her hand on her chin.

That's a choice, given the performative aspects of a high-stakes presidential debate. Harris is betting that showing active disdain for Trump will play well with viewers.

Harris successfully baited Trump over his rallies

Roughly 25 minutes into the debate, Harris said something unusual: She urged viewers to attend one of Trump's rallies, noting that he often speaks of fictional characters while claiming that attendees often leave early. That visibly angered Trump.

"People don't go to her rallies, there's no reason to go," Trump said, claiming that Harris pays people to attend her rallies. "People don't leave my rallies."

From that moment on, Trump's tone took a noticeable turn, with more frequent yelling and hyperbole.

Trump refused to say whether he would veto a national abortion ban

One of the most intense exchanges of the debate was over abortion, when Harris delivered intense remarks on the consequences of state-level abortion bans.

Trump insisted that he would not sign a national abortion ban, saying that the overturning of Roe v. Wade was sufficient. But when Trump was pressed on whether he would veto such a ban, he repeatedly declined to say, despite Sen. JD Vance declaring he would do so in a recent interview.