President Obama's message to voters in new DNC ad: 'It's going to be close'

Former President Barack Obama has a message for Democrats in the campaign's waning days. "It's going to be close," he says in a new get-out-the-vote digital ad -- a subtle nod to efforts to avoid a similar fate as 2016.

The warning comes as part of the Democratic National Committee's broader push to engage voters ahead of Election Day, with voting already underway in 48 states plus the nation's capital.

"The 2020 election isn't a few weeks away; it's already here. Millions of Americans are already voting; make sure you stand up and join them," Obama says in the ad. "It's going to be close. It could come down to a handful of voters just like you. So I'm asking you to bring this thing home. Leave no doubt. Vote early."

Democrats, anxious to thwart the complacency among the party's base that helped deliver the White House for Donald Trump four years ago, are harnessing the influence of Obama to animate voters that may have sat out before or are voting for the first time.

"There will always be reasons to think your vote doesn't matter -- that's not new," Obama says. "What is new is a growing movement for justice, equality and progress on so many issues. This really is a tipping point, and that momentum only continues if we win this election."

The ad, which is part of a seven-figure advertising campaign according to a Democratic aide, will target voters across 11 battlegrounds: Arizona, Florida, Georgia, Iowa, Michigan, Minnesota, Nevada, North Carolina, Pennsylvania, Virginia and Wisconsin. It will also reach voters in Nebraska's 2nd Congressional District, an Omaha-area seat that Democrats' are eyeing this cycle. (Nebraska splits its electoral votes -- awarding two votes to the winner in each congressional district, and the remaining two to the statewide winner.)

Earlier this week, Obama appeared in a DNC video encouraging voters to learn about their options for casting a ballot with state-specific tutorials across 24 states amid the seismic shift to mail-in voting in the middle of a pandemic.

More than 15 million Americans have already voted early, an unprecedented number just under three weeks out from Election Day, according to the U.S. Elections Project, spearheaded by University of Florida professor Michael McDonald. That total so far is nearly five times the roughly 3.2 million who voted at a similar point four years ago, when then-candidate Hillary Clinton saw less-than-stellar turnout, particularly among the party's core constituencies, according to Pew Research Center.

For Obama, his latest foray into electoral politics, with calls to "bring this thing home," reflects his accelerated role in the pivotal closing weeks of the campaign to help reclaim the White House for his former vice president.

He is expected to hit the campaign trail "soon" for Joe Biden, the party's standard-bearer, an aide to the former president told ABC News.

While Obama has yet to stump for Biden in any of the battleground states -- mostly due to the greatly reduced in-person footprint the former vice president's team has stuck to amid the ongoing pandemic -- he has actively boosted his former running mate and Democrats up and down the ballot.

Between several fundraisers on behalf of Biden's campaign, a prime-time speech during the virtual Democratic National Convention in August, podcast appearances and in emails to supporters, Obama has served as one of the most prominent character witnesses for Biden and has vouched for his leadership after eight years together in the White House.

As the most sought-after figure in the Democratic Party, he's also elevated lower-profile Democrats as part of their efforts to recapture the Senate and defend their majority in the House with endorsements and fundraisers.

On Friday, he's joining five senate candidates for a grassroots fundraiser, including Sen. Gary Peters, D-Mich.; Theresa Greenfield, who is challenging Sen. Joni Ernst, R-Iowa; MJ Hegar, who is seeking to unseat Sen. John Cornyn, R-Texas; Jon Ossoff, who is running against Sen. David Perdue, D-Ga.; and Ralph Warnock, who is competing in Georgia's special election against Sen. Kelly Loeffler and Rep. Doug Collins.

Democrats, keenly aware of his post-presidency popularity, are hoping Obama can energize a base that recent polling shows is not as enthusiastic about their nominee compared to Trump and his supporters.

"President Obama is a powerful voice -- he motivates every part of the coalition that will help elect Joe Biden, Kamala Harris and Democrats at every level of the ballot," said David Bergstein, a spokesperson for the DNC. "His message about the urgency of this election cuts through the noise in the closing weeks of the campaign and will help ensure that every American has a plan to vote and make their voice heard."

ABC News' John Verhovek contributed to this report.