ATLANTA (AP) — Midterm elections are less than three weeks away, yet more than 904,000 Americans already have cast their ballots, with almost 60 percent of those early votes in Florida, according to data compiled by The Associated Press from election officials in 11 states.

Those numbers are climbing daily as more states begin their advance voting periods and more voters return mail-in ballots ahead of Nov. 4.

Early voting doesn’t predict electoral outcomes, but both major parties emphasized the opportunity in recentelections as they try to lock in core supporters. Thirty-three states and the District of Columbia allow some form of advance voting other than traditional absentee voting requiring an excuse.

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A spokesman for national Democrats, Justin Barasky, said the party is especially focused on encouraging early voting by Democrats who usually don’t participate in midterms. Returns show that, historically, casual voters who support Democrats in presidential elections are more likely to stay home than average Republican voters.

In the 2010 midterms, when Republicans regained control of the House and won sweeping victories in statehouses around the country, advance voting accounted for almost 27 million ballots out of more than 89 million, meaning about 3 out of 10 voters cast early ballots. Almost 129 million people voted in the 2012 presidential election, 35.8 percent of them before Election Day.

This year’s midterms will determine which party controls the Senate for the final two years of President Barack Obama’s administration. Republicans are expected to pad their House majority. There are also 36 governor’s races.

Noteworthy figures from around the country:

— FLORIDA: Republican Gov. Rick Scott faces a tough re-election challenge from Democrat Charlie Crist, himself a former Republican governor who switched parties to run for his old job. GOP voters account for 48.3 percent of the 535,000 ballots already cast, with registered Democrats comprising 34.5 percent.

More than 2.35 million people voted early in Florida four years ago, while the 2012 number neared 4.8 million. It’s worth noting that Republicans led in the early stages in 2012 — a turnabout from Obama’s first presidential campaign. Yet Obama ended up carrying Florida a second time anyway, suggesting that sometimes turnout drives don’t turn up new votes, they just get reliable supporters to vote using a new process.

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— IOWA: In a state key to Senate control, registered Democrats account for 45 percent of the 151,656 early ballots returned in Iowa, with Republicans at 39 percent and independents at 16 percent. Republican Senate candidate Joni Ernst hopes to pick up one of the six additional seats the GOP needs for a majority. Rep. Bruce Braley also seeks to succeed Democrat Tom Harkin, who is retiring.

— GEORGIA: With two high-profile races, almost 67,000 Georgians already have voted, about 8.5 percent of the 2010 advance vote total. Republican David Perdue and Democrat Michelle Nunn are in a tight Senate race to succeed Republican Saxby Chambliss, who’s retiring. Democratic state Sen. Jason Carter, the former president’s grandson, wants to unseat Republican Gov. Nathan Deal.

This could be a state where many voters cast ballots before seeing all the twists and turns. Nunn is just ramping up her attacks on Perdue, a former corporate CEO, for saying he’s “proud” of outsourcing jobs to foreign locales. Republicans on Wednesday started circulating video of Nunn declining to answer a conservative activist who asked her whether she voted for Obama.

— NORTH CAROLINA: The battle between Democratic Sen. Kay Hagan and Republican challenger Thom Tillis is intense, but mail-in ballots are only a trickle since in-person advance voting has yet to begin. Through Wednesday morning, election offices had received just 10,000 returned early ballots, just 1 percent of the 2010 total. The early vote watch in North Carolina comes amid pending litigation over several election law changes adopted by Tillis and his fellow Republican lawmakers.

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