Election 2020 undecided races: When we'll know more about the presidency, key states and Senate contests

The presidency remained undecided as of Friday morning.

This year, according to the United States Election Project, more than 100 million Americans cast early votes, either on early voting days or using mail-in ballots.

Of the races still being decided, the presidency most notably hangs in the balance, as key states, including Georgia and Pennsylvania continue to count votes. Down the ballot, key Senate races are similarly still being decided.

Here's what you need to know as votes are counted and 2020's races continue to be projected.

Overall: The presidency is still up for grabs

President Donald Trump is projected to take the battleground state of Florida, but Arizona, Pennsylvania and Georgia still hang in the balance as a possibility for former Vice President Joe Biden as of Friday morning.

Undecided swing states:

Georgia: Georgia's race is not yet projected.
Why not? Gabriel Sterling, who oversees the statewide voting system in Georgia, told ABC News that election officials are still counting thousands of votes. Military and overseas ballots can still come in on Friday, according to Sterling.

North Carolina: North Carolina's race is not yet projected.
Why not? North Carolina counts absentee ballots that arrive as late as Nov. 12. North Carolina also requires a sample audit count to ensure the reliability of election results tabulated by a machine, so following the general election, the state board of elections will randomly select precincts, early voting sites and ballots to be counted by hand in each county.

Arizona: Arizona's race has not yet been projected.
Why not? Arizona still has votes being counted on Friday.

Nevada: Nevada's race has not yet been projected.
Why not? It's Nevada's first time sending mail-in ballots to all active registered voters. The state is accepting ballots that arrive by Nov. 10.

Pennsylvania: Pennsylvania's race has not yet been projected.
Why not? Pennsylvania's three largest counties -- which sent out the most absentee ballots to voters, will continue counting their mail-in ballots. Absentee ballots will not be fully counted until Friday at the earliest after deadlocked negotiations between Democratic Gov. Tom Wolf and Republicans who control the state legislature.

Key Senate races undecided:

Alaska: Sen. Dan Sullivan (R) vs. Dr. Al Gross (I)
Alaska's Senate race is not yet projected.

Georgia: Sen. David Perdue (R) vs. Jon Ossoff (D)
Georgia special election: Sen. Kelly Loeffler (R) vs. Rep. Doug Collins (R) vs. Rev. Raphael Warnock (D)
Both the Georgia Senate election and the Georgia special election are projected to go to a runoff on Jan. 5.

North Carolina: Sen. Thom Tillis (R) vs. Cal Cunningham (D)
North Carolina's Senate race is not yet projected.