(AFP) - More than 27 million people have already voted in the US presidential election, and early trends are offering some hints of the outcome less than a week before Election Day.

Six days before the election, voters had cast 6.7 million more early ballots compared to the same period in 2012, the data analytics firm Catalist said.

The numbers hold both good news and bad for Democratic candidate Hillary Clinton as she battles her Republican challenger Donald Trump in a tightening final dash for the White House.

Early voting tallies indicate Democrats are turning out in greater numbers than Republicans in some states, an advantage for Clinton, experts say.

But turnout is lagging among young people and African Americans, key constituencies that lifted a triumphant Barack Obama into the White House in 2008.

In Chicago -- the popular president's adopted hometown and the country's third-largest city -- however, there is little sign of the enthusiasm deficit reflected in national polls.

Early voting here is on pace to match or exceed 2012, when the country's first black president won a second term, and officials say polling places fill up around midday with voters on their lunch breaks.

"It's very important to me to carry on what Obama started," said Democrat Deborah Land, 61, outside an early voting station in downtown Chicago.

That kind of sentiment should help Clinton -- who has cast herself as Obama's loyal heir and guardian of his legacy -- by driving Democrats to the polls.

Clinton was Obama's bitter rival for the Democratic nomination in 2008, but later served as his secretary of state and is now aiming to make history as the first female president of the United States.

But both she and Trump are deeply unpopular, with unusually low favorability ratings -- 44 percent for Clinton and 38 percent for Trump, according to an average of multiple polls by RealClearPolitics.

And after one of the meanest US presidential contests in memory, many voters are motivated less by support for their own candidate than opposition to the other.

Mark Baker, a Clinton voter, said he felt compelled this year "because of the nature of the election, and frankly, Mr Trump."

"It's been a long election season," the 57-year-old said. "I think everybody is eager for it to be over with, except Saturday Night Live" -- the hit comedy show that parodies the campaign.

- Email probe -

Last week's surprise revelation that the FBI is looking into Clinton's emails again has injected renewed uncertainty into the race.

A new Washington Post-ABC tracking poll showed Trump ahead of Clinton 46 to 45 percent -- the first time that survey put him first since May.

More significantly, the poll found the number of Clinton supporters who were enthusiastic about her candidacy dropped from 51 to 43 percent, while Trump's numbers remained unchanged at 53 percent.

Still, Michael McDonald of the University of Florida, who maintains a national tally of early voting, said it is unlikely early voters will be swayed.

"People have consumed a lot of information about the candidates and they've made up their minds, and they're going out and voting," he said.

So far, there are signs of enthusiasm among early voters who are Latino, women and white liberals.

"The worrisome signs for (Clinton's) campaign are the lower early voting rates for blacks and young people. They were essential pieces of the coalition that elected and reelected Obama," said Barry Burden, professor of political science at the University of Wisconsin-Madison.

- 'Checkmate' -

Trump faces bigger hurdles.

They include Clinton's early vote lead in the swing states of Nevada, Virginia and Colorado, according to McDonald.

"That's almost like checkmate because Trump would have to win almost every other battleground state," he said.

On top of that, Latino voters overwhelmingly support Clinton, with a record 27.3 million of them eligible to vote in this election -- four million more than during the last presidential race, according to the Pew Research Center.

"Compared to 2012, it appears that early voting is being used more by Latinos," Burden said. "This might reflect the efforts that the Clinton campaign has made into the Latino community and concerns among Latinos about what Trump has said about immigrants."

Meanwhile, Trump has had to defend his position in reliably Republican states.

Among them, Texas is seeing outsize enthusiasm from early voters. More than a quarter of the state's eligible voters had cast their ballots a week before the November 8 election, shattering records.

With recent poll numbers in the state showing Clinton closing in on Trump's lead, the early voting figures are especially intriguing observers, even prompting speculation about whether deeply red Texas might turn blue.

"The fact that the state is perceived to be competitive... is driving both parties to the polls," said Brandon Rottinghaus, a political science professor at the University of Houston.

Although Clinton is still unlikely to win Texas, he added, the former secretary of state could lose by a much smaller margin than past Democrats.

"That will be a success for them," he said, helping Democrats in future elections.

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