UPDATE 9-Romney goes on offensive in first debate with Obama

Steve Holland and John Whitesides

* Romney zeroes in on weak economic growth

* Obama says Romney tax plan doesn't add up

* Snap poll gives debate edge to Romney

DENVER, Oct 3 (Reuters) - Mitt Romney battled back in his

uphill drive to oust President Barack Obama on Wednesday with an

aggressive debate performance that put his campaign on a more

positive footing after weeks of stumbles and knocked Obama

off-stride.

In the first of three presidential debates this month,

Romney went beyond expectations as the two candidates stood

side-by-side for the first time after months of campaigning

against each other from long distance.

Looking to claw his way back into a race that has seen Obama

hold an edge among voters, Romney was on the offensive

throughout the 90-minute encounter with Obama. While the

president landed some punches on Romney's tax plan, he did not

appear as prepared as his rival and missed several opportunities

to attack.

With under five weeks to go until the Nov. 6 election, it

was uncertain whether Romney had managed to change the

trajectory of a race that has favored Obama. It is difficult to

dislodge an incumbent from the White House. In recent weeks,

Romney has lurched from stumble to stumble and been unable to

project a consistent message.

"How does it translate into the horse race? That's unclear,"

said Steven Schier, a political science professor at Carleton

College in Minnesota. "Romney should have some momentum. The

question is whether he can maintain it."

But there was no question that Romney's campaign felt it was

now in a better position. In the "spin room" afterward, Romney

advisers hung around for 90 minutes talking to reporters, long

after the Obama side had decamped.

A CNN/ORC snap poll said 67 percent of registered voters

surveyed thought Romney won the debate at the University of

Denver, compared with 25 percent for Obama.

Romney and Obama clashed repeatedly over taxes, healthcare

and the role of government in ways that reflected the deep

ideological divide in Washington and that has contributed to

political gridlock.

Romney zeroed in on weak economic growth and 8.1 percent

unemployment that have left Obama vulnerable in his effort to

win a second four-year term. Government has taken on too big a

role under Obama, dampening job creation, Romney argued.

"What we're seeing right now, in my view, (is) a

trickle-down government approach, which has government thinking

it can do a better job than free people pursuing their dreams.

And it's not working. And the proof of that is 23 million people

out of work," Romney said.

Fact checkers took issue with some of assertions by the

former Massachusetts governor, like the number of people

unemployed, but he appeared more poised and better prepared than

his opponent.

Obama argued that under his leadership, the economy had been

brought back from the brink, with 5 million jobs created in the

private sector, a resurgent auto industry and housing beginning

to rise.

"You know, four years ago, we were going through a major

crisis. And yet my faith and confidence in the American future

is undiminished," Obama said.

NO MENTION OF THE '47 PERCENT'

Mysteriously, Obama failed to mention issues his campaign

has used in attack ads to damage Romney such as the Republican's

now infamous "47 percent" video, job cuts he made while at Bain

Capital private equity firm, his tax returns and previous hard

line on immigration.

The debate saw no haymaker punches thrown and not much in

the way of memorable one-line zingers. Instead, it was a war of

attrition as each man used facts and figures to make his points

and stress the differences between them.

Romney, however, did himself some favors with crisper

answers than Obama, who sounded professorial and a bit

long-winded despite his staff's best efforts to get him to give

snappier comments.

Quite often Obama looked downward at his notes as Romney

pounced on the president's record. At one point, the Democrat

quibbled with debate moderator Jim Lehrer who tried to cut him

off for going over his allotted time.

"I had five seconds before you interrupted me," Obama said

to Lehrer with a smile.

Romney's chances of winning the White House were up by 8.4

percentage points after the debate, although he was still only

34.3 percent assured of victory in November, according to online

betting site Intrade.

The incumbent did put Romney on the defensive about his

proposals for overhauling the U.S. tax system with a 20 percent

across-the-board tax cut. Obama said it would cost the

government $5 trillion and that it would be impossible to make

up this amount by eliminating tax loopholes as the Republican

talks about.

"The fact is that if you are lowering the rates the way you

described, Governor, then it is not possible to come up with

enough deductions and loopholes that only affect high-income

individuals to avoid either raising the deficit or burdening the

middle class. It's - it's math. It's arithmetic," Obama said.

Romney insisted his tax plan would not cost $5 trillion,

saying, "Virtually everything he said about my tax plan is

inaccurate."

Obama also reminded Americans that Romney was proposing more

of the same kind of tax cuts that Obama's Republican

predecessor, former President George W. Bush, pushed through

Congress in 2001 and 2003. Most Americans are willing to concede

that Obama inherited an economic mess, but also believe it is

his responsibility to bring back the economy.

"We ended up moving from surpluses to deficits and it all

culminated with the worst recession since the Great Depression,"

said Obama.

In the face of attacks from Romney that the Obama healthcare

overhaul of 2010 will hurt small-business hiring, Obama

basically said his healthcare plan was modeled after the program

Romney put in place as governor of Massachusetts, and it "hasn't

destroyed jobs" there.

After arguing for months that the Wall Street regulation

legislation known as "Dodd-Frank" should be repealed, Romney was

forced to concede under pressure from Obama that he would keep

some financial regulations established under the law.

ROMNEY NEEDED VICTORY MORE

Romney was in need of a victory in the debate to help him

put his campaign back on a positive footing after a rocky few

weeks.

He was damaged by a hidden-camera videotape in which he said

47 percent of voters were dependent on government and unlikely

to support him. That was among several stumbles that have

knocked Romney's campaign off message.

Obama, holding a slight lead in national polls and leading

Romney in some swing states where the election will be decided,

was looking in the debate to avoid harming his position as the

apparent front-runner.

But he may have spent too much time trying to avoid making

mistakes and let Romney get the better of him.

The debate was the best opportunity to date to reach large

numbers of voters in an unfiltered way, with an estimated

television audience of 60 million possible.

Advisers to both Romney and Obama predictably said their man

emerged victorious. Obama adviser David Plouffe told reporters

in the spin room that Romney appeared "testy" at times.

As for Obama's lengthy comments, his campaign manager Jim

Messina said, "That's never going to be our strong suit."

Romney adviser Eric Fehrnstrom said if the debate had been a

prize fight, the referee would have called it for Romney an hour

in.

The debate was the first of three such face-offs scheduled

in the next four weeks. Biden and Romney's running mate, U.S.

Representative Paul Ryan, will debate once, on Oct. 11.