WASHINGTON — Hillary Clinton may not be accumulating the type of early-vote advantage her campaign wanted, but she continues to maintain an apparent edge over Donald Trump, with roughly one-fourth of all expected ballots cast in the 2016 election.

The Democrat’s campaign once hoped to bank substantial votes from Democrats in North Carolina and Florida before Election Day. Both are must-win states for Donald Trump.

But data about the early vote suggest she’s not doing as well as President Barack Obama in 2012. Ballot requests from likely supporters have been weak in parts of the Midwest, and African-American turnout has fallen, too.

Still, the tens of millions of early votes cast also point to strength from Democratic-leaning Latino voters, potentially giving Clinton a significant advantage in Nevada and Colorado. With more than half the votes already cast in those states, Democrats are matching if not exceeding their successful 2012 pace, according to data compiled by The Associated Press.

“We are seeing the trajectory of the election change in some states, but Democrats are also making up ground,” said Michael McDonald, a University of Florida professor and expert in voter turnout.

Early voting — by mail and at polling stations — is under way in 37 states. More than 31 million votes have been cast, representing nearly 25 percent of the total votes expected nationwide if turnout is similar to 2012. In all, more than 46 million people — or as much as 40 percent of the electorate — are expected to vote before Tuesday, according to AP data.

The results of those votes won’t be known until polls close next week. But early voting data — party affiliation, race and other details — are being carefully examined for clues about the ballots that have been cast so far.

In North Carolina and Florida, Democrats did better with mail balloting than they had in previous elections. They expected to build on that with the start of in-person voting, where Democrats traditionally do well. But the big turnout — especially among black voters — hasn’t yet happened.

In North Carolina, with nearly half of the expected vote already cast, Democrats lead in ballots submitted, 43 percent to 32 percent. But that’s slightly below the same period in 2012, when Mitt Romney narrowly won the state.