Three-term Democratic Sen. Bill Nelson of Florida, trailing Republican challenger Rick Scott by more than 55,000 votes as of 12:50 a.m. ET, will make a "full statement tomorrow," a campaign spokesperson said early Wednesday.

“This is obviously not the result Senator Nelson's campaign has worked hard for," the spokesperson said. "The senator will be making a full statement tomorrow to thank all those who rallied for his cause."

Moments earlier, White House press secretary Sarah Sanders said in a statement that President Donald Trump had made congratulatory calls to winning Republican Senate candidates, including Scott.

The race is too close to call, according to an NBC News projection. 

With 99 percent of the vote tallied, Scott, the outgoing GOP governor, had 50.3 percent of the vote, while Nelson had 49.7 percent. However, Florida has a mandatory recount rule if candidates are within 0.5 percent of each other. 

If Scott wins, it would add to the GOP's growing cushion in the Senate. Republicans had, as of 12:30 a.m. ET, successfully held several seats they were defending (including in Tennessee and Texas) and picked up two other seats held by Democrats in Indiana and Missouri.