The Obama campaign has a message for its supporters: We're winning -- in early voting, that is.

Yet the Romney campaign also has a message: You're not.

Vice President Joe Biden picked up the charge on Friday in Florida, telling supporters, "Folks, if you look around the country, like in places like Iowa, there's early voting."

"I hope it keeps up because we're winning the early voting," Biden added, encouraging voters in the Sunshine State to also vote early.

Biden's comments came during a rally in Sun City Center - an area in Florida's Hillsborough County, some 25 miles south of Tampa. The area, predominantly populated by seniors, is vote rich and attractive to both campaigns. Minutes after Biden landed at the Tampa airport, Republican vice presidential nominee Rep. Paul Ryan landed there for a nearby rally. Both Air Force 2, which carries Biden, and Ryan's campaign plane sat on the tarmac not far from each other.

Biden's focus on early voting echoed a claim - from a memo circulated earlier Friday by the Obama campaign -- regarding Ohio.

After citing the number of Obama for America campaign offices in Ohio, National Field Director Jeremy Bird wrote that the campaign is currently "ahead of where we were at this time against John McCain - and ahead of Mitt Romney."

The first claim in Bird's memo: "All public polling shows that the President has a double-digit lead among those who have voted."

Biden's boast is bolstered by some numbers.

As of Friday afternoon, Iowa's Secretary of State reported that 477,718 Iowans had requested absentee ballots - with just over 301,000 of those ballots cast.

It's the party breakdown that could prove encouraging for Democrats.

Nearly 46% of the absentee ballots requested in Iowa have been Democratic while nearly 31% have been Republican.

Biden did not specifically refer to these numbers as he claimed the Obama campaign is winning the early vote nor did he cite sources.

Some questioned the claims.

"We don't know if a registered Democrat will vote for Barack Obama and we don't know if a registered Republican will vote for Mitt Romney," Michael McDonald, associate professor government and politics at George Mason University, told CNN. McDonald specializes in elections.

There are other reasons to view early voting claims with skepticism.

For one, Republicans in Iowa have recently made gains in one measure of early voting.

According to the Des Moines Register, "Republican voters' requests for ballots have eclipsed the Democrats for 10 straight days, significantly shrinking President Barack Obama's advantage, according to state records through Oct. 12."

Meanwhile, the Romney campaign is beating back Democrats' claims.

On Monday, the campaign distributed to reporters a memo from Romney Political Director Rich Beeson.

In it, Beeson cited a Reuters/Ipsos poll which said the Obama campaign led in early voting.

"This claim can easily be proved flawed and untrue," Beeson wrote, laying out many reasons for that argument.

Beeson added: "Many of the Democratic ballots are from high propensity voters who would almost certainly be voting on Election Day - meaning that President Obama is cannibalizing his turnout on November 6th. Governor Romney's early voting effort has been, and will continue to be, focused on low propensity voters, which means his Election Day turnout will not be negatively impacted by the early vote program."