Democrats lead in early voting in Iowa, Nevada

In two of the most competitive states in the presidential race, Iowa and Nevada, Democrats are building a significant advantage in early voting.

Who has the edge is more muddled in the bigger swing states of Ohio and Florida. Republicans have a narrow lead in Colorado. Early in-person voting started in Florida over the weekend, and dozens of Democrats in Tallahassee marched five blocks from a church to a voting site Sunday, chanting "Vote early."

More than 14 million people have already cast ballots nationwide, according to the U.S. Election Project at George Mason University in Fairfax, Va. Both parties are spinning their versions of what the turnout means with more than a third of the nation's vote likely to be cast before Election Day, a week from Tuesday.

"The data are confirming what we are seeing in the polling, which is that these state races are going to be narrower than in 2008," said Michael McDonald of George Mason who studies early voting.

In Iowa, more than 470,000 people had cast ballots through Saturday, the Iowa secretary of state's office said. If as many people vote this year as did in 2008, that would represent 30 percent of the total vote. Registered Democrats have cast 44.6 percent of the ballots so far, compared with 32 percent by Republicans and 23.3 percent by independents.

By the end of this week, McDonald said, the proportion of early voting in Iowa, as compared with 2008's total vote, could grow to 45 percent. If current trends for ballots requested and returned remain unchanged, he said, President Barack Obama's advantage could become almost insurmountable for Republican challenger Mitt Romney.

In Colorado, Florida, Iowa and North Carolina, Obama banked so many early votes in 2008 that he won those states even though he ran behind in each in votes cast on Election Day itself, according to voting data compiled by The Associated Press.

In Nevada, where an even larger proportion of the vote has been cast than in Iowa, compared with 2008, Democrats have accounted for 45.4 percent, according to the Nevada secretary of state's office. Republicans have accounted for 37.2 percent and independent voters for 17.4 percent.