(CBS News) WASHINGTON - Democrats opened a new line of attack on presumptive Republican presidential nominee Mitt Romney Thursday, focusing on his term as governor of Massachusetts nearly 10 years ago.
, but what do those polls mean, with more than five months to go before the election?
Campaigning in the swing state of Iowa Thursday night, Mr. Obama continued to hammer Romney for his time as the head of a successful private equity firm.
"There may be value in that kind of experience. But it's not in the White House," the president said to a cheering crowd.
Romney's campaign events in West Philadelphia focused on education, which he called the civil rights issue of our time.
Going into summer, polls have the candidates in a statistical dead heat, but, as any previous candidate will tell you, polls in May don't mean much in November.
In May 2004, the last time a sitting president ran for re-election, George W. Bush was losing by eight points to John Kerry.
But after a tough campaign on national security and growing economic confidence, Mr. Bush won.
By contrast, his father was the incumbent in 1992 and, in May of that year, was leading Bill Clinton. But over that summer, Americans' confidence in the economy dropped, and George H.W. Bush lost his lead and the White House.
"Anything that hurts the U.S. economy right now does not help the president," National Journal White House correspondent Major Garrett said.
According to numbers from the pollster Gallup, the economic and political climate today is more similar to years when incumbent presidents lost than when they won.
"At this stage of his presidency, seeking re-election, President Obama is weaker than Jimmy Carter, who lost, stronger than George H.W. Bush, who lost, and weaker than every modern American president who sought re-election and won," said Garrett. "They were all above 50 percent approval. The president is not. He's around 46 percent. That's a danger zone."
There are other troubling signs for the president.
For 20 years, Gallup has asked voters whether they're satisfied with the way things in the country are going. Today, only 24 percent say they're satisfied. That's closest to the 20 percent low in May 1992, in George H.W. Bush's only term.
For winning presidents, those numbers were higher. In May 2004, under George W. Bush, 36 percent were satisfied; under Mr. Clinton in May 1996, 37 percent were.
But voters say they like Mr. Obama, that he seems more likeable and seems to care more about average Americans. His favorability ratings are to his advantage, which makes this race, going into the summer, a toss-up.
To see Jan Crawford's report, click on the video in the player above.