The surge of early voting — which could see one-third of the nation's voters turn out before Election Day — is giving Hillary Clinton an important boost in swing states."All the data we are seeing suggests that Clinton is doing as well, if not better, than Obama in many, if not most, places," said Patrick Murray, director of the Monmouth University Polling Institute.So far, an estimated 7.2 million people have voted nationwide, and the news is promising for Clinton in Florida and North Carolina. Polls show the race too close to call in North Carolina and Clinton up slightly in Florida. Without those states' 44 electoral votes, Donald Trump's prospects of reaching the 270 needed to win are dim.

Most Florida counties began in-person voting Monday. Republicans have been returning mail ballots at a rate only slightly higher than Democrats. That's bad news for the GOP, which at this point four years ago had a 5-point advantage in early voting and still lost the state to Barack Obama by 1 point.

Reluctant to embrace Trump

While some of the difference can be attributed to changes in how early voting proceeds, it also reflects how many of the state's Republicans have been reluctant to embrace Trump.Joel Hawksley, a retired Winter Park Army veteran, plans to cast an early vote for state and local Republicans. He's not so sure about Trump.

"I haven't felt comfortable with him yet," Hawksley said.Trump backers say he'll do fine."We've been lied to by politicians for decades. You can keep your doctor. Your insurance will go down. It's ridiculous. I'm just tired of politicians," said Michael Dugre of Orlando, an early voter who is unemployed.

Too close to call in N.C.

North Carolina remains too close to call, and while early voting signs for Clinton are encouraging for her, she can't claim they give her a decisive boost. Early voting began last week, and about 9.5 percent of the state's 6.8 million voters have cast ballots.Registered Democrats are voting more heavily than Republicans and unaffiliated voters so far. But Democrats also appear to be voting at a slightly slower pace than in 2012.

"Clinton appears to hold a sizable lead among early voters, but Trump is staying close because of his large lead among white voters who have not yet cast their ballots," said Murray, who polls in the state.

Democratic advantages

Other states report more notable Democratic advantages, notably on the Eastern Seaboard and in Arizona, Colorado, Nevada and Wisconsin.Nevada early voting began last week, and registered Democrats are far outnumbering Republicans in ballots cast so far. "Republicans have to be worried," wrote Nevada analyst Jon Ralston on his blog.

The early vote findings do come with a warning: "Democrats are pleased, but we still have a very crucial period ahead," said Michael McDonald, a Florida-based election consultant and professor who analyzes early voting trends.

Early voting methods vary widely from state to state, and can include in-person voting, mail and other means. With early voting accelerating this week — eventually 37 states and the District of Columbia will have some form of it — predicting who has an advantage will become more difficult. Results are not announced until polls close on Election Day.

Upside for Trump

Trump can point to some bright spots. In Ohio and Iowa, early voting trends suggest he's doing better than Republicans have in the past.

In the Cleveland and Columbus areas, two places where Democrats have to do well, requests for mail absentee ballots are way down. That could be because of a quirk: In 2012, the state mailed ballot requests to any registered voter, while this year they were mailed only to those who had voted in the last two elections.

An analysis by McDonald found that in all other Ohio counties, absentee ballot requests are up. That's not encouraging for Clinton."GOP voters tend not to want to vote early. You hear it on doorsteps all the time," said Scott Jennings, who ran Republican nominee Mitt Romney's Ohio campaign in 2012.

Clues point to winner

While no one knows for sure how people are voting, the ballot requests provide important clues. "Based on modeling and prior history you can make some pretty good assumptions about how it is going," he said.

In Iowa, Republican ballot requests are up slightly while Democrats are down. That's no surprise, because it's the one swing state where Trump has been doing better than Obama did in 2012.

Both political parties have sophisticated systems for identifying and motivating voters to turn out. Both give voters scores that describe a person's potential for voting the way the party wishes.

Getting out the vote

Democrats update their data nightly. They tend to focus during the early vote period on turning out those who are sporadic voters and may need an extra push. Republicans contend that Democrats are not bringing new voters into the system."Democrats are shifting around voters who would have voted in past elections and in many states they're trailing where they were four years ago," contended GOP spokeswoman Lindsay Walters.

Republicans update their scores every Sunday. Scores include what issues matter most, whether they'll vote Republican and whether they're likely to turn out.

By midweek, the GOP is able to identify who's most likely to vote its way. If the score also shows they need motivation to turn out, the party will contact the voters via mail or phone or dispatch volunteers to speak with them.