Bill Plante

Bill Plante is a CBS News Senior White House Correspondent

CBS News) WASHINGTON - A new Politico-George Washington University poll shows Mitt Romney leading President Obama by one point, 48 to 47 percent.

In that poll, independent voters prefered Romney by a ten-point margin.

Over the weekend, meanwhile, the president formally started campaigning for another four years in office.

Unofficially, the president's re-election campaign has been under way for several months.

If you look at his speeches to large audiences in swing states, they look and sound a lot like campaign rallies.

But over the weekend, he made it official - and if you live in one of the key states he needs to carry, you're starting to see campaign ads like this: "We're coming back because America's greatness comes from a strong middle class. Because you don't quit, and neither does he."

The Obama campaign was out Monday morning with its most significant ad buy yet, in 9 states, touting the administration's accomplishments during the president's first term.

Full CBSNews.com coverage: Election 2012

It came as Mr. Obama officially launched his campaign in two key states, Ohio and Virginia.

"We are still fired up! We are still ready to go!" he told backers at one rally.

The president hit Republican rival Mitt Romney on a number of fronts.

On women, he said, "We don't need another political fight about ending a woman's right to choose, or getting rid of Planned Parenthood."

On Romney's view of big corporations: "I don't care how many ways you try to explain it: Corporations aren't people. People are people."

And he showed off his new campaign motto: "Forward."

"The question that will actually make a difference in your life and in the lives of your children," the president said, "is not just about how we're doing today. It's about how we'll be doing tomorrow."

The Romney campaign hit back, accusing the president of moving the goal posts for success to a second term, and arguing that Americans aren't better off now than they were four years ago.

Despite a brutal primary battle, polls show Romney will be competitive in the 11 battleground states where this campaign will be fought.

And former Romney rival Newt Gingrich said on the CBS' "Face the Nation" Sunday that Republicans are now united on the core issue of the election.

"The choice," Gingrich said, "is the most radical president in American history and a failed president at the economy and somebody who has a solid record on jobs and who, in fact, on basic principles, is a conservative."

"Conservative" is one of the tags Mr. Obama will try to pin on Romney, recycling Romney's attempts to appeal to tea party voters during the Republican primaries.

Meanwhile, the president may have a little work to do to boost enthusiasm among his own supporters: Even though there were 14,000 people at one of those rallies over the weekend, there were still 4,000 empty seats.

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