Democrats building mail-in ballot advantage, but will it hold?

Mail-in ballots being returned in Florida are giving Democrats hope that they are on their way to beating President Trump in November.

With just 21 days until the election, there are 1.8 million ballots already collected. With that many days to go in 2016, only 521,000 were in.

"That has largely to do with COVID," said Democratic strategist Kevin Cate. "But it also continues an increase we have seen over a number of years with mail ballots, people are choosing it with convenience."

On Tuesday, Cate tweeted that 904,000 ballots have been returned by Democrats, and 519,000 have been returned by Republicans.

That gives Democrats a lead of 384,000.

Compare that to 2016, when their pre-Election Day lead was 88,000 and they lost the state by just under 113,000.

"Republicans are listening to Donald Trump when it comes to vote-by-mail," said Cate.

RELATED: Florida's vote-by-mail tally climbs to 1.8-million

But Republicans say Democrats should be careful of what they wish for.

"I am not as concerned as some people are because when you look at the data, the data starts telling you a different story," said Donald Trump campaign surrogate Blaise Ingoglia.

He says their data shows that only 13% of the most reliable Republican voters have turned in ballots, compared to 25% of reliable Democrats.

"They are not adding any more voters, all they are doing is shifting the way they vote," said Ingoglia.

Voting in Florida 2020: Tampa Bay area election guide

To make sure your vote counts, there are several things to know about early voting in Florida and voting by mail in 2020. Here is county-by-county information about voting deadlines and methods in the Tampa Bay area.

Further, he says the GOP registration efforts, has shrunk the Democratic registration advantage from about 330,000 four years ago to about 185,000 today.

"We are expecting a huge wave of Republicans to vote late in the election and on election day," said Ingoglia. "Right now they are cheering and spiking the football, but wait until later."

To that, Cate says his data shows 20% of Democratic ballots are coming from those who didn't vote in 2016, and that 30% of No Party Affiliated ballots returned are from new voters, which he believes will skew Democratic.

"I would caution anyone to be too optimistic, but I'd certainly rather be on the Democratic side than the Republican side as it stands today," said Cate.