Republican presidential nominee Donald Trump and Democratic presidential nominee Hillary Clinton sparred over video of Trump's lewd remarks and former president Bill Clinton's past scandals, Oct. 9 at the second presidential debate in St. Louis. (The Washington Post)

He vowed to put her in prison. He stalked across the stage, and hovered imposingly behind her. At one point, he referred to her as “the Devil.”

Rather than being chastened by the most serious crisis of his presidential campaign, GOP nominee Donald Trump came forth in full alpha-male mode for his second debate with Democratic nominee Hillary Clinton on Sunday night.

It made for a discomfiting 90 minutes, for the 40 undecided voters in the audience at Washington University in St. Louis, who had planned to put their everyday concerns to the two candidates, and for the millions who watched the contenders glare at each other across a split screen.

Yes, there was a brief apology for what Trump dismissed as “locker-room talk” in a recently unearthed 2005 video in which he had spoken crudely about women. In the video, first reported by The Washington Post, Trump boasted that his celebrity entitled him to make sexual advances toward women that included grabbing their genitals.

But Trump quickly deflected with a non sequitur: “But it’s locker-room talk, and it’s one of those things. I will knock the hell out of ISIS.”

Republican presidential nominee Donald Trump responded Hillary Clinton saying that he shouldn't be in charge of the law in the U.S. saying, "You'd be in jail." The comment was met with rousing applause from the audience. (The Washington Post)

Traditionally, the town hall is expected to be a more convivial format than the other two general-election debates. It is one in which the candidates are challenged to relate to voters, making a personal connection and putting forward solutions to the problems they confront.

That did not happen Sunday. Instead, the candidates assumed a combative stance. They did not even engage in the formality of an opening handshake.

Even before the debate began, Trump made it clear that he intended to be on offense, when he held a 3 1/2 -minute news conference with four women who claimed they had been mistreated by Clinton or her husband, former president Bill Clinton.

They included Paula Jones, a former Arkansas state employee who had accused then-Gov. Bill Clinton of sexual harassment in the early 1990s, and Juanita Broaddrick, who claimed that Clinton had raped her in 1978, when he was Arkansas attorney general. All four were also in the audience for the debate.

Trump said that the comments he made in the video were “something that happened. If you look at Bill Clinton, far worse. Mine are words, and his was action.”

For her part, Hillary Clinton sought to make a broader indictment against Trump, saying his comments about women reflect a broader intolerance that extends to other groups.

“This is who Donald Trump is,” Clinton said of the video. “But it’s not only women, and it’s not only this video that raises questions about his fitness to be our president, because he has also targeted immigrants, African Americans, Latinos, people with disabilities, POWs, Muslims and so many others.”

“The question for us, the question our country must answer is that this is not who we are,” she added.

Clinton, who has long experience with the town hall format, demonstrated more ease in that setting, moving frequently toward the audience as she gave her answers. She often turned her back on her opponent, leaving him to glower at her in the background of the television frame.

His crude comments on the video were not the only problem that Trump was facing as the debate began. Clinton had been widely considered to have put in a stronger performance at their first faceoff at Hoftstra University. She now leads in polling in every battleground state.

In bringing up Bill Clinton’s marital infidelities, Trump was working from a well-worn playbook, used by foes of the Clintons repeatedly over the past quarter century.

It has usually backfired.

The saga over Bill Clinton’s affair with White House intern Monica Lewinsky led to his December 1998 impeachment by the Republican-led House.

That very week, however, Clinton’s job approval reached 73 percent in the Gallup poll, which was the highest point of his presidency.

The Lewinsky scandal also brought an outpouring of public sympathy for then-first lady Hillary Clinton, whose favorability topped 65 percent in some polls, which was the most popular she had ever been. That wave of support also helped launch her subsequent career as a politician in her own right.

Trump himself had been among those who expressed compassion for Hillary Clinton and her public humiliation.

“I think she’s gone through terrible times,” Trump told CNN in November 1999. “I think she’s been through more than any woman should have to bear.”

The Democratic nominee has been put on the defensive before about allegations regarding her husband’s past sexual behavior.

Last November, Hillary Clinton tweeted: “Every survivor of sexual assault deserves to be heard, believed, and supported.”

In December, a woman in the audience at a Clinton campaign event in New Hampshire asked her: “You say that all rape victims should be believed. But would you say that about Juanita Broaddrick, Kathleen Willey and/or Paula Jones?”

Clinton responded awkwardly: “Well, I would say that everyone should be believed at first until they are disbelieved based on evidence.”

Trump had telegraphed that this was the direction that he intended to go as well, and this time, the Democratic nominee was not caught off guard.

“He gets to run his campaign any way he chooses. He gets to decide what he wants to talk about,” Clinton said. “Instead of answering people’s questions, talking about our agenda, laying out the plans that we have that we think can make a better life and a better country, that’s his choice.”

And it is likely to set the tone for the remaining four weeks of the election.