Democrat Andrew Gillum announced Saturday he was conceding his hard-fought race for Florida governor to his Republican rival, Ron DeSantis, vowing to keep fighting until he wins an election.
Gillum, who was aiming to become the state's first black chief executive, had vowed to keep in the race until every single vote was counted.
The race had gone to a recount, with results due by a Sunday deadline, as has a narrow Senate race between outgoing governor Rick Scott and incumbent Democrat Bill Nelson.
"I want to congratulate @RonDeSantisFL on becoming the next Governor of the great state of Florida," tweeted Gillum.
"We are going to keep fighting. We will keep working. And in the end, I believe that we will win. I am so thankful to each and every one of you."
Florida produced some of the nation's closest results in the November 6 midterm elections, including DeSantis's apparent narrow victory over Gillum.
"I can tell you, this has been the journey of our lives," Gillum said in a video posted on Facebook alongside his wife, R Jai.
For the Senate race, unofficial results show incumbent Nelson trailing Scott by about 12,600 votes out of more than 8.2 million cast, or 0.15 percentage points.
That narrow margin triggered a hand recount of problematic ballots, such as those where a voter filled in bubbles next to the names of Nelson and Scott.
Results are scheduled to be certified Tuesday.
Trump has repeatedly charged that Florida's elections were marred by vote fraud, but state and local authorities have said there is no evidence of wrongdoing.
In the neighbouring state of Georgia, Democrat Stacey Abrams, who was aiming to become the country's first ever black female governor, conceded to Republican Brian Kemp, Georgia's secretary of state.
They only had about a single percentage point between them.
She contemplated further legal action in the race, but her legal burden would have proven extremely steep.
In her concession speech on Friday, she cited hours-long lines at polling stations, thousands of voter registrations frozen before the election, and polling sites shuttered.
Andrew Gillum, who was aiming to become the state's first black chief executive, had vowed to keep in the race until every single vote was counted.