CHICAGO (Reuters) - President Barack Obama won the endorsement of retired General Colin Powell, a moderate Republican, on Thursday as he and Republican rival Mitt Romney engaged in frantic campaigning in battleground states to try to turn a razor-close race their way.

Hoping to encourage supporters to vote ahead of the November 6 election, Obama cast his ballot early in his home town of Chicago.

Romney portrayed himself as an agent of change during a day campaigning in Ohio with 12 days to go until the election.

There was little movement in the overall state of the race - which is essentially tied. Romney was clinging to a one percentage point lead over Obama in Thursday's Reuters/Ipsos daily tracking poll, up 47 percent to 46 percent for Obama.

A new ABC News/Washington Post poll showed how Romney has made up ground since defeating Obama in the first of their three presidential debates on October 3. The poll had Romney up by 50 percent to 47 percent among likely voters.

Romney charged that electing Obama would return Washington to a "status-quo path," a path that "doesn't have an answer about how to get the economy going."

"The path we're on does not have new answers," said Romney, whose campaign has been centered around ways to create jobs in the sputtering economy.

Powell's endorsement was a milestone for the president in his re-election bid but since he had backed Obama four years ago, it did not have the same impact this time around.

Powell was a secretary of state during the presidency of Obama's Republican predecessor, George W. Bush. He told CBS he is sticking with Obama because the economy is improving.

"The unemployment rate is too high. People are still hurting in housing. But I see that we are starting to rise up," he said.

'I NEED OHIO'

Showing off his own momentum, Romney appeared at a rally in Defiance, Ohio Thursday night where a campaign-estimated 12,000 people turned out to hear Romney after a concert by Big and Rich, Meat Loaf and Randy Owen of country music group Alabama.

"We need to take America back, and I need Ohio," Romney said. "And Ohio's going to set the course for the nation."

Obama has generated large crowds during a two-day, eight-state tour that is taking him to Iowa, Colorado, Nevada, Florida, Ohio, California, Illinois and Virginia.

Some 8,500 people showed up for an early morning rally in Tampa, Florida on Thursday and some 15,000 came out for the president in Richmond, Virginia.

The president has sought to rev up enthusiasm and momentum in those crowds by talking about his cross-country trip.

"We are right in the middle of our 48-hour fly-around campaign extravaganza," he said to applause in Florida. "We pulled an all-nighter last night!"

The election will likely be decided in a handful of swing states where the candidates are spending just about all of their time, with none of them more important than Ohio.

The two campaigns squabbled over who has the upper hand in Ohio, where the race is close. Democrats believe they have the edge with an early voting and turn-out operation, but Republicans disagree.

"A steady upward trajectory among key voting blocs indicates a close race, but one that is unmistakably moving in Mitt Romney's direction," said Romney national political director Rich Beeson in an e-mailed memo.

The Romney campaign made clear it would have enough money to fund television advertising in the swing states by announcing his campaign had brought in more than $111 million from October 1 to October 17. The Romney campaign and its Republican allies reported having $169 million cash on hand for the final push.