President Barack Obama and his Republican opponent Mitt Romney faced the nation Wednesday night in their first televised debate, sparring over everything from taxes to medicare -- and the best way to revive the U.S. economy.

The debate at the University of Denver centred on domestic issues, as Obama accused Romney of trying to resurrect some of the same policies that contributed to the economic meltdown four years ago, and Romney countered that the president wants to “crush” the middle class with tax hikes.

Obama said he entered the White House with “more than a trillion dollar deficit waiting for me,” which included two wars -- in Iraq and Afghanistan -- that “weren’t paid for.”

“Governor Romney has a perspective that says if we cut taxes skewed toward the wealthy and cut back regulations, we’ll be better off. I have a different view,” he said.

Romney said his economic plan will put Americans back to work and create new jobs, contrary to Obama’s proposals.

“Middle-income families are being crushed,” he said.

“When we’re in recession, you shouldn’t raise taxes on anyone.”

The two rivals were friendly at first, however.

In his opening remarks, Obama addressed his wife, Michelle Obama, as “sweetie,” wishing her a happy wedding anniversary. The couple married 20 years ago Wednesday.

"I'm sure this is the most romantic place you could imagine, here with me,” Romney joked as he congratulated the couple.

Throughout the debate, Romney often touched on what he called his five-point plan: energy, trade, independence, education and training, balanced budget and small business.

When Romney said that he would repeal financial regulations approved after the 2008 economic crisis, Obama retorted: "Does anyone think there is too much oversight and regulation of Wall Street?"

Obama also said Romney’s plan to reduce tax rates by 20 per cent would cost the country $5 trillion. Romney countered that the president’s assertion of his tax plan was “inaccurate.”

On the health care front, Obama continued to tout his reforms to the system, which aim to make medical insurance accessible to all Americans. Romney said Obama’s health care law weakens the system by putting Americans’ health care choices into the government’s hands. Obama, on the other hand, said Romney would turn medicare into a private system that would gut programs for seniors.

Romney came into Wednesday night’s debate with plenty of experience: he has participated in 19 debates this year during the Republican primary. Obama’s last high-profile debate was in 2008 with then-Republican opponent John McCain.

Political commentators and casual observers on social media sites like Twitter and Facebook noted Romney’s aggressive approach to the debate, with many saying he was well-prepared and surprisingly feisty.

Others said Obama didn’t live up to his usual strong performances on stage.

Romney and Obama’s next debate is on Oct. 16 in New York, followed by another one in Florida on Oct. 22.

Vice-President Joe Biden and Romney's running mate Paul Ryan will face off in an Oct. 11 debate in Kentucky.

With files from The Associated Press