DES MOINES, Iowa -- In a presidential race seemingly frozen in place for months, the advantage has shifted toward President Barack Obama after a series of miscues by Mitt Romney, punctuated by the Republican challenger's comments about people who pay no income tax.
Despite a continuing gray economic sky and unrest in the Mideast, the president has edged ahead of Romney in polls in some of the most competitive states, including Iowa and Virginia, and forced Romney to redouble efforts in Florida and Ohio, without which he has little chance of becoming president.
With about six weeks left before Election Day and early voting under way in some states, Romney faces a problematic map, a ticking clock and a campaign demeanor that has failed to click with many voters.
Obama's momentum did not come overnight. It built over several weeks in which Romney hit some potholes while the president made few errors and benefited from previously unseen advantages in advertising strategy and fundraising.
Weeks of campaigning remain, and the three debates, starting Oct. 3, are the kind of events that could change the momentum again. But the race has bent toward Obama at a pivotal moment, according to public and internal campaign polls as well as interviews with leading Democratic and Republican strategists in the most closely contested states.
"Months of paid media about Romney not caring about people, being out of touch ... it came into complete focus with Romney making the case against himself," Democratic strategist Tad Devine, a top aide to past Democratic nominees Al Gore and John Kerry, said about a video that surfaced last week of Romney speaking at a private fundraiser in May.
The polls show trouble rising for Romney almost everywhere he looks. He has fallen dangerously behind in Virginia and Ohio, and his ability to close in on Obama in Iowa and Wisconsin is now in doubt.
The polls suggest that Romney must do more than inch his way up in a handful of states. He must win overwhelming shares of undecided voters, maximize the GOP's turnout, and suppress Obama's turnout where he can.
GOP officials say it's too early to count Romney out.
"Maybe he can't wait forever. But, today, a strong Romney effort offering good policy as opposed to the awful, failed policies of Obama ... will prevail," said former Mississippi Gov. Haley Barbour, a past national GOP chairman. "It's our election to win, and stakes are too high to let it get away."
Most of the polls were conducted before there was widespread publicity of the video secretly recorded in May. In it, Romney tells donors that the roughly 47 percent of Americans who do not pay income tax will support Obama and "are dependent upon government" and "believe that they are victims."
The revelation overshadowed Romney's promise to sharpen his campaign approach and offer more specific proposals to improve the economy. Democrats said the video played into their portrait of Romney as a wealthy politician out of touch with ordinary people.
Romney may not have helped himself later in the week when he released his 2011 tax return. It showed that he and his wife paid $1.94 million in federal taxes on income of $13.7 million. Their effective tax rate was 14.1 percent, lower than many families pay, because most of the couple's earnings come from investments.
Strategists in both parties have different explanations for Romney's slippage in the polls.
Some say millions of Americans started paying serious attention to the race during the two parties' conventions, when Democrats seemed to make a better impression. Former President Bill Clinton's detailed defense of Obama was especially effective, it seems.
Other campaign veterans say Romney has failed to present a cogent vision for where he wants to take the country. His message sometimes seems vague or confusing, as when he pledges to slash federal spending and then criticizes Obama for promising to squeeze $716 billion from Medicare.
Obama has his presidential powers to appeal to voters. One example was his naming of a new national monument in sharply contested Colorado.
On the foreign front, he announced new actions against Chinese export subsidies while campaigning in Ohio. That move came shortly after Romney made what was widely seen as a premature criticism of the administration in the early hours of Muslim attacks on U.S. officials and buildings in the Middle East.
Some strategists say Obama was wise to campaign aggressively during the Republican convention. He also kept his ads on the air in battleground states, while Romney went dark during the Democratic convention and stopping campaigning to prepare for the debates.
Whatever the reason for the shifts in polls, they have rocked the Romney campaign in states such as Virginia, which Romney badly needs to return to the Republican column. Until Obama's win in 2008, Virginians had not rejected a GOP presidential nominee since 1964.