Trump aggressively blamed the nation's chronic problems on Hillary Clinton yet found himself mostly on the defensive in their first debate here Monday night as she accused him of racist behavior, hiding potential conflicts of interest and "stiffing" those who helped build his business empire.

After circling each other for months, Clinton and Trump finally took the stage together for the first time, and each tried in a series of combative, acrimonious exchanges to discredit the other.

Trump, the Republican nominee, spent nearly the entire evening explaining himself - over his temperament, treatment of women and minorities, business practices and readiness to be commander in chief, as well as over his long perpetuation of a falsehood about Barack Obama's birthplace to delegitimize his presidency.

"He has a long record of engaging in racist behavior, and the birther lie was a very hurtful one," said Clinton, the Democratic nominee. "Barack Obama is a man of great dignity, and I could tell how much it bothered him and annoyed him that this was being touted and used against him."

Trump, who earlier this month at last acknowledged Obama's birth in Hawaii, replied by invoking Clinton's 2008 rivalry with Obama: "When you try to act holier than thou, it really doesn't work."

In an earlier exchange, when Clinton said it was unfortunate that Trump paints a dire picture of the livelihoods and economic circumstances of many African-Americans, Trump groaned in apparent disgust.

The 95-minute debate at Hofstra University on New York's Long Island pitted two historically unpopular and polarizing nominees against each other. The television networks were preparing for as many as 100 million people to watch, which would put Monday night's debate in the pantheon of the Super Bowl.

The clash came at a critical juncture in the campaign. With six weeks until Election Day, and with voters in some states already starting to cast ballots, polls show Clinton's summer lead has all but evaporated. Trump is effectively tied in many of the battleground states where Clinton had enjoyed comfortable leads.

Clinton poured forth with policy details and practiced catch phrases - "Trumped-up trickle down" to describe his tax plan, for instance - and tried to sow doubts about the seriousness of Trump's proposals. She seized on his comments about Russian President Vladimir Putin to suggest that Trump does not understand the global threats the country faces.