Washington, Oct 4 (IANS) Republican challenger Mitt Romney put up a tough fight against President Barack Obama as the two sparred over jobs, taxes and healthcare in the first presidential debate.

US presidential debates are a time-honoured tradition, with the first nationally-televised presidential debate being held in 1960.

Taking the offensive right from the word go in the 90-minute encounter, Wednesday night in Denver, Colorado, Romney made good use of a gaffe by Vice President Joe Biden to suggest that the middle class had been "buried" under Obama's economic policies.

"I just don't know how the president could have come into office, facing 23 million people out of work, rising unemployment, an economic crisis at the kitchen table, and spend his energy and passion for two years fighting for Obamacare instead of fighting for jobs for the American people," he said.

Obama, on the other hand, sounded somewhat professorial to begin with as he was forced to defend his record of four years in office while he charged his opponent with vowing to undo a host of his reforms without specifying what he would do instead.

"At some point, the American people have to ask themselves if the reason that Governor Romney is keeping all these plans secret is because they're too good," he said.

It was only half-way through the 90-minute encounter that Obama, celebrating his 20th wedding anniversary, realised what he was up against and came into his own to brand the Romney tax plan to reduce deficit by eliminating deductions while lowering taxes as a $5 trillion cut.

"I think math, common sense and our history shows us that's not a recipe for job growth," Obama said, echoing a line from former president Bill Clinton at last month's Democratic convention saying the math doesn't add up without increasing tax revenue.

Romney disagreed with Obama's characterisation of his tax plan, saying it won't add to the deficit, and criticised Obama's call for allowing tax rates on income over $250,000 for families and $200,000 for individuals to return to the higher rates of the 1990s.

Depicting Obama's vision as one of big government, Romney insisted that while regulation was necessary to keep the economy functioning, the Dodd-Frank Act passed in response to the financial crisis of 2008 was in some cases excessive.

He also repeated criticism of Obama's signature Affordable Care Act, dubbed Obamacare by opponents that passed with no Republican support amounted to an unnecessary and unwanted government takeover of health care.

"The right answer is not to have the federal government take over health care," Romney said.

As they moved on to the topic of the role of the government, Obama stressed the federal government has a role to play in opening up opportunity and create ladders of opportunity.

"There is also something we do better together," said Obama.

Romney said the role of the government is to protect the principals of the Constitution and the Declaration of Independence, but not to substitute for people's initiatives, decrying what he called a "trickle down government".

Voters seemed to agree with the critics in giving Romney the upper hand in the debate with a CNN snap poll of debate watchers saying 67 percent believed Romney was the winner, and 25 percent believed Obama was the winner.

The other presidential debates will occur Oct 16 in New York and Oct 22 in Florida. Vice President Joe Biden and House member Paul Ryan, Romney's running mate, will debate on Oct 11 in Kentucky.

While the first nationally-televised presidential debate was not held until 1960, several other debates are considered predecessors to the presidential debates, including the debates between Abraham Lincoln and Stephen Douglas in the middle of 19th century.

The first nationally-televised general election presidential debate was held on Sep 26, 1960, between John F. Kennedy and Richard Nixon.

It wasn't until 1976 that presidential debates became a formality of the presidential election.

(Arun Kumar can be contacted at arun.kumar@ians.in)