COLUMBUS/CHICAGO (Sept 27): Hillary Clinton and Donald Trump clashed sharply over trade and the U.S. economy as they opened their first presidential debate, in a rancorous start to a highly anticipated event that put on display their sharp differences over the nation’s fiscal future.

Just moments into the debate, the session devolved into charges and counter-charges between the candidates. Clinton accused Trump of not paying federal income taxes for years, and spoke of workers he "stiffed" by not paying them.

Trump said Clinton was the type of failed politician who doesn’t understand how to run a business and is driving the country into ruin. "It is about time that this country had someone running it that understood something about money," he said.

The event at Hofstra University in Hempstead, New York, marked the first time that voters got to see the major-party nominees on the same stage for a widely anticipated debate that promised to be a pivotal moment in a close and bitterly fought contest.

What they saw was a combative Clinton who went on attack over Trump’s main bonafides for president -- his business record -- and Trump, supposedly preparing a more subdued approach, return quickly to his fiery ways.

The former secretary of state presented Trump as being in the middle of the housing crisis that caused the financial crisis and a recession. "Donald was one of the people who rooted for the housing crisis," she said.

"That’s called business, by the way," Trump interjected, as Clinton was made her case against him.

"I have a feeling by the end of this evening I’m going to be blamed for everything that’s ever happened," Clinton said at one point.

"Why not?" Trump interjected. Clinton then shot back that Trump was just "saying more crazy things" in the debate.

"There’s nothing crazy about not letting our companies bring their money back into their country," he said.

After Clinton repeated her calls for Trump to release his tax returns, as has been tradition for the past four decades among presidential nominees, Trump said he would, although with conditions connected to the e-mails that are missing from Clinton’s personal server when she was secretary of state.

"I will release my tax returns against my lawyer’s wishes when she releases her 33,000 emails that have been deleted," Trump said. "As soon as she releases them, I will release my tax returns."

Trump also targeted the Federal Reserve, as he displayed the combative nature that has been a hallmark of his campaign.

"The Fed is being more political as Secretary Clinton," Trump charged, repeating his claims that monetary policy is being manipulated to help Democrats in this campaign season, a claim Fed Chair Janet Yellen has repeatedly denied.

"We are in a big fat ugly bubble and we better be awfully careful,” Trump said. "And we have a Fed that’s doing political things. Janet Yellen of the Fed, the Fed is doing political things by keeping interest rates at this level.”

Trump lashed out at trade with China and Mexico as he has throughout the campaign. He said the U.S. was being put at a disadvantage. China, he said, is “using our country as a piggy bank.’’

Clinton responded that Trump’s economic plan is the “most extreme version’’ of standardRepublican rhetoric. “I call it trumped up trickle-down.’’

For his part, Trump went after Clinton for her past support of the North American Free Trade Agreement. "You called it the gold standard of trade deals," he said.

"Donald, I know you live in your own reality," Clinton responded.

"You are going to drive business out," Trump said. "I will bring back jobs. You can’t bring back jobs."

At one point, Clinton said, "I have a feeling that by the end of the debate I’m going to be blamed for everything."

"Why not?" Trump shot back.

Among those in the audience were the spouses of the candidates, former President Bill Clinton and Melania Trump, who shook hands before they were seated. Moderator Lester Holt, of NBC News admonished the audience to refrain from cheering or clapping during the 90-minute session.

Heading into the debate, staged 43 days from the Nov. 8 election, Trump and Clinton are tied at 46 percent in a head-to-head contest among likely voters, according to the latest Bloomberg Politics national poll. Trump, the Republican nominee, gets 43 percent to Democrat Clinton’s 41 percent when third-party candidates are included.

The uncertainty about the election outcome and soft support for both candidates raise the stakes for the debate, the first of three scheduled, said Frank Fahrenkopf Jr., co-chairman of the Commission on Presidential Debates. Viewers will be watching for revealing moments about Trump’s temperament and depth of knowledge on issues and whether Clinton can convey trustworthiness that surveys suggest many voters doubt, he said.

“I think it’s going to have a bigger effect probably than any debate we’ve had in a long, long time,” Fahrenkopf said.

A third of registered voters said the debates will be important to their decision in the presidential race, according to a Wall Street Journal/NBC News poll conducted Sept. 16-19.

With the partisan lines hardening as the election draws closer, Clinton and Trump are looking to appeal to a segment of voters, between 3 and 10 percent depending on the poll, who say they are undecided between the two candidates. In a race as tight as this one, a movement of a few percentage points in that group to one candidate or the other could mean a margin of victory.

Clinton has an additional target audience: those who so far aren’t motivated and aren’t likely to vote on Nov. 8. For the first time, the Bloomberg survey asked unlikely voters who they would back if they did vote. What it showed is greater support for Clinton than Trump among that group and that they have a profile skewed to typical demographic strongholds for Democrats.

Also raising the pressure on the candidates are polls consistently showing that more than half of voters view both of them negatively, said Ben Ginsberg, a former Republican National Committee counsel who has helped negotiate terms for past presidential debates and prepare candidates. Debates give them a chance to recast the impressions voters have formed of them in the past months of campaigning.

“These stand to be pivotal moments in the campaign, just because these are the two least popular candidates in history,” Ginsberg said. “So each one gets a second chance to make a first impression, really.”

Both campaigns sought before the debate started to manage expectations, with Trump complaining in advance that the media coverage will favor Clinton and Clinton suggesting that Trump will be held to a lower standard in judging who wins.

Clinton faces a higher bar to clear, according to the Bloomberg poll, which was released Monday. Forty-nine percent say they anticipate the former secretary of state will perform better, while 39 percent say that for Trump.

Absent from Monday night’s debate were Libertarian Party nominee Gary Johnson and the Green Party’s Jill Stein. Neither reached the threshold of 15 percent average support in recognized polls to qualify under the debate commission’s rules.

Counting people who will watch on television and on computers and mobile devices, viewership could exceed 100 million, Fahrenkopf said. The record for televised debates is 80.6 million for the 1980 debate between Ronald Reagan and Jimmy Carter, according to Nielsen.