Democrat Hillary Clinton accused her rival Donald Trump of pushing a “racist lie” that President Barack Obama was not born in the United States.

“It can’t be dismissed that easily. He has really started his political activity based on this racist lie that our first black president was not an American citizen. There was no absolutely no evidence for it. But he persisted, he persisted year after year,” Clinton said Monday at the first presidential debate of the general election campaign. She cited 1970s lawsuits, in which Trump was accused of discriminating against black tenants: “He has a long record of engaging in racist behavior.”

Trump claimed credit for pushing the false notion that President Obama was not born in the United States, saying that “I think I did a good job.”

“Nobody was pressing it, nobody was caring much about it,” Trump said, when moderator Lester Holt asked why he had continued to support the “birther” theory, even after Obama had released his birth certificate from Hawaii. “But I was the one who got him to produce the birth certificate, and I think I did a good job.”

Holt had asked Trump what he would say to black voters, who were unhappy that Trump has persisted so long with the false notion.

Earlier, Trump said that African-Americans and Hispanics in U.S. cities are “living in hell,” because the cities are so violent. He said he would restore “law and order,” in part by using the aggressive stop-and-frisk enforcement tactics once employed by the New York city police.

“Secretary Clinton doesn’t want to use a couple of words, and that’s law and order. We need law and order. If we don’t have it, we’re not going to have a country,” Trump said. “We need law and order in our country.”

Holt told Trump that stop-and-frisk tactics had been ruled unconstitutional, because it disproportionately targeted blacks and Hispanics.

“No, you’re wrong,” Trump said, blaming a judge who was biased against police, and blaming a New York City administration for giving up on the case. “The argument is that we have to take the guns away from these people. … These are people that are bad people.”

Trump declined again to release his income-tax returns, offering two explanations — first, that his returns were under audit and second, that the returns would not be that revelatory anyway.

“You don’t learn that much from tax returns, that I can tell you,” the GOP nominee said, after Holt had questioned the first rationale, saying that the IRS would not prohibit the release of tax returns under audit.

That exchange came during a period in which Clinton sharply criticized Trump over his taxes, suggesting that perhaps Trump had not paid any income taxes in recent years.

“That means zero for troops, zero for vets, zero for schools and health,” Clinton said.

Trump did not seem to push back against that suggestion. At one point, when Clinton suggested that Trump should have paid more taxes to improve the country’s infrastructure.

“It would be squandered too, believe me,” Trump said.

Trump responded by saying that his business acumen was exactly what the country needs now: “We have a country that’s doing so badly, that’s being ripped off by every single county in the world. That’s the kind of thinking that our country needs.”

The first presidential debate of the general election campaign turned unusually contentious in its first half-hour, with Trump repeatedly interrupting Clinton, and Clinton telling Trump, “Donald, I know you live in your own reality.”

At one particularly unusual moment, about 25 minutes in, Trump attacked Clinton for posting her plan to fight the Islamic State on her website. That, he said, was not something that Gen. Douglas MacArthur — a leader of American forces in World War II and the Korean War — would have done.

“Well, at least I have a plan to fight ISIS,” Clinton said.

“You’re telling the enemy everything you want to do,” Trump said.

Trump frequently talked over Clinton’s responses. Later, Clinton said she felt that Trump had blamed her for things beyond her control.

“Why not?” Trump said.

Clinton, who was said to have prepared to deal with an unpredictable opponent, still seemed caught off guard: “Just join the debate by saying more crazy things,” she said, seeming to assemble a zinger one word at a time.

The debate began with Trump bemoaning the state of the country, and Clinton bemoaning Trump.

Trump, the GOP nominee, answered the first economics-focused questions of Monday night’s debate by saying that the U.S. was being hoodwinked and taken advantage of by Mexico, China and other countries. He talked about manufacturing jobs leaving the U.S., and promised — as he had in the primary — to impose penalties on companies that take jobs offshore.

“Our country’s in very deep trouble. We don’t know what we’re doing,” Trump said. Of countries like China, he said, “What they’re doing to us is a very, very sad thing.”

Clinton began her first answers with an appeal to common purpose, talking about her 2-year-old granddaughter. But she quickly turned to attacks on Trump, saying that he had rooted for the housing-market collapse a little less than a decade ago (“That’s called business, by the way,” Trump interjected), and saying that Trump would raise the debt by offering huge tax cuts to high earners.

“I call it Trumped-up trickle down, because that’s what it would be,” Clinton said, referring to the trickle-down economics model of the 1980s.

In its early going, the presidential debate featured some interjections from Trump, who tried to interrupt Clinton when she said (correctly) that Trump had called climate change a hoax.

Clinton and Trump came into Monday virtually tied in national polls. Both candidates have been relying on negative messaging, in which the best selling point for each has been that the other candidate is worse.

For both, this debate will offer a chance to build a positive image of their own.

Underscoring the unique nature of the combatants, Clinton’s debate preparations included a focus on Trump’s personality as well as the substance of what will be discussed onstage at Hofstra University in Hempstead, New York, according to several Democrats with knowledge of her campaign’s approach.

After days of preparing for the 90-minute debate at a hotel near her home in Westchester County, Clinton departed for Long Island early Monday afternoon to continue her preparations, according to a campaign aide. She was joined by former President Bill Clinton on the ride over.

The stakes Monday could hardly be higher for both candidates. A new Washington Post-poll released Sunday shows likely voters split nationally 46 percent for Clinton and 44 percent for Trump, with Libertarian Party nominee Gary Johnson at 5 percent and Green Party nominee Jill Stein at 1 percent.

With barely six weeks remaining until Election Day, Clinton’s camp — after a prolonged focus on trashing Trump — sees the debate as a chance for her to present what she actually hopes to accomplish as president and to ease voters’ deep concerns about her likability and trustworthiness.