WASHINGTON, United States (AP) — Hillary Clinton appears to be displaying strength in the crucial battleground states of North Carolina and Florida among voters casting ballots before election day, and may also be building an early vote advantage in Arizona and Colorado.

Donald Trump, meanwhile, appears to be holding ground in Ohio, Iowa and Georgia, according to data compiled by The Associated Press. Those are important states for Trump, but not sufficient for him to win the presidency if he loses states like Florida or North Carolina.

“The Trump campaign should be concerned,” said Scott Tranter, co-founder of Optimus, a Republican data analytics firm. His firm’s analysis suggests a “strong final showing for the Clinton campaign” in early voting.

Early voting — by mail or at polling stations — is off to a fast start. More than 5.3 million votes have been cast already, far outpacing the rate for this period in 2012. Balloting is underway in 34 out of 37 early-voting states.

In all, more than 46 million people are expected to vote before Election Day — or as much as 40 per cent of all votes cast.

Both parties are encouraging their supporters to vote early. The outcome of those ballots won’t be known until counting begins after polls close on November 8, but some clues are available. Some states report the party affiliations of early voters, as well as breakdowns by race and gender.

The data that is available represents a small sample of the more than 120 million people who will cast ballots in the presidential election, but a notable one.