President Trump's recent gains in South Florida and Miami-Dade County are making Joe Biden's campaign nervous.

In the state's most populous county, the incumbent has outspent the former vice president by about $4 million on TV, with much of it on Spanish-language ads.

In addition, Politico reported Tuesday that conservative allies of the president have begun messaging Spanish speakers on WhatsApp.

BIDEN, TRUMP DEADLOCKED IN BATTLED GROUND FLORIDA: POLL

Miami-Dade County Republicans have fielded candidates in five key local races, all of whom are Cuban American.

New local polling released this week found that Biden is underperforming Hillary Clinton’s 2016 margins in the critical county. His campaign has since added Latino staff members in the Sunshine State and focused more on his media effort in Miami-Dade County as well.

Democratic presidential candidate former Vice President Joe Biden arrives at the Allegheny County Airport in West Mifflin, Pa., en route to speak at a campaign event in Pittsburgh on Monday, Aug. 31, 2020. (AP Photo/Carolyn Kaster)

Democratic vice presidential nominee Kamala Harris and her husband are scheduled to campaign in Miami on Thursday.

The Biden campaign has also launched a national voter outreach campaign that will work in tandem with Latino business leaders to promote their message of entrepreneurship, according to the Miami Herald.

The Trump campaign is betting that by competing hard in widely Democratic areas, it can go on the offensive in other parts of the state.

Trump has also been in South Florida many times during his term in office.

The president's continuous outreach in Miami-Dade has garnered support from many Cuban American voters over the years, and 72% of registered Republicans are Hispanics. Biden has more support with non-Cuban Hispanics.

Neither the Cuban American vote nor the Hispanic vote are unbending, however, and a growing wave of Pan-Latin American voters account for almost half of Florida’s registered Hispanic voters.

Florida has 29 electoral votes, and it's one of the largest swing-state prizes in the Electoral College.

In 2012, former President Barack Obama won Miami-Dade by 4 percentage points and clinched Florida's Hispanic vote with 60% of the vote. Four years later, though, he narrowly lost the statewide Cuban American vote to Utah Republican Mitt Romney 48% to 52%.

Clinton won Miami-Dade County by 30 percentage points -- or 290,000 votes -- in 2016 and defeated Trump for the statewide Hispanic vote 62% to 35%. However, she trailed Obama's performance with Cuban American voters, trailing Trump 41% to 54%.

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Florida is known for its tight races.

Obama carried the state by 2.8% and 0.88% margins in 2008 and 2012, and the president won by 1.2% in 2016.