The 1.6M voters who could determine the US election don't currently reside in the country

Now, with Harris and former President Trump locked in a virtual dead heat just two weeks before Election Day, this bloc could carry more influence than ever. 

Democrats, for their part, are wasting little time in seizing upon what they see as a crucial demographic of U.S. voters overseas. 

Earlier this year, the DNC announced a $300,000 investment in the group "Democrats Abroad," aimed at helping mobilize U.S. voters overseas. 

The investment is a first-of-its-kind donation from the DNC during a presidential campaign cycle, a spokesperson told Fox News. 

It seeks to ramp up voter registration efforts by U.S. voters overseas, educate residents about registration and mail-in voting operations, and widely mobilize the population. They have also taken out ads on social media.

Voters living overseas do face additional challenges in casting their votes, which must be submitted - often by mail - to the state in which they are registered. 

Additionally, 47% of military voters living abroad participated in the 2020 election but just 8% of non-military voters cast their ballots from overseas - a statistic Democrats are hoping to change.

In an email to Fox News, a spokesperson for the DNC noted that President Biden's narrow 44,000-vote advantage in the battleground states of Arizona, Georgia and Wisconsin helped carry him to victory in 2020. 

Abroad voters had a notable difference in at least two of those states - Georgia and Arizona - and also played a key role two years later in the outcome of the close 2022 midterm races.

Now, as the race tightens even further in its final weeks, Democrats see this bloc as potentially offering Harris a winning edge.

"This election will be won on the margins, and every single vote counts," DNC deputy communications director Abhi Rahman told Fox News in a statement.

The push comes as Republicans in at least three swing states have sought to crack down on overseas voting in the final sprint to Election Day. The Republican National Committee and state-level groups in Pennsylvania, Michigan and North Carolina have filed lawsuits this month seeking additional restrictions on a vetting and verification process they argue is devoid of proper safeguards.

As of this writing, two judges in Michigan and North Carolina rejected the lawsuits, which they said were devoid of evidence and risked disenfranchising voters. 

"We're going to win this election by engaging every eligible voter, no matter where they live," Rahman told Fox News, adding that their investment "shows our commitment to leaving no stone left unturned."