With election day just three days away, attention is quickly turning to the counties that might determine the winner of the 2020 presidential election. In Miami-Dade, Florida’s biggest county, a strong Republican voter turnout is putting Democratic candidate Joe Bidens chances at a victory in jeopardy. Florida is one of the most consequential swing states, and both Biden and President Donald Trump held campaign events in the Sunshine State on Thursday. Biden’s supporters gathered in Broward County, and Trump held a rally in Tampa, vying for the state’s 29 electoral votes.

In order for Biden to take home Florida, a huge voter turnout in Miami-Dade, one of the few blue counties in Florida, is crucial. But Democrats are currently turning out at lower rates than their Republican counterparts and at lower rates than they were at this point four years ago, when Hillary Clinton won by 29 percentage points but still lost the state.

To date, nearly 63% of the 428,000 registered Republicans in the county have voted so far, whereas about 56% of the county’s 634,000 registered Democrats have voted, according to state data. Although these numbers do reveal that more Democrats have voted in the state overall, Biden would have to win by a massive margin in order to offset Trump’s guaranteed victories in the majority of the state’s red regions.

According to Rep. Frederica Wilson (D-Florida), one of the challenges the Biden campaign faced was its decision to discourage field staff from knocking on doors during the pandemic and its subsequent delay in funding a return to this form of canvassing. “We did not get the kind of funding for different vendors who would do that type of work until late in the campaign,” Wilson said.

But the Democrats haven’t given up hope. Many blue voters are casting mail-in ballots which have yet to be counted, and some recent polls even have Biden leading Trump by a few percentage points.