Donald Trump apparently just obliterated Marco Rubio in Florida

Donald Trump has apparently won a key state that could put him one step closer to securing the GOP presidential nomination.

CNN and others projected Tuesday evening that Trump would win Florida, a valuable primary state which awards all of its delegates to the highest-performing candidate, rather than divvying them up proportionally.

Trump tweeted about his expected win shortly after voting ended in some parts of the state at 7 p.m. ET.

"Word is that, despite a record amount spent on negative and phony ads, I had a massive victory in Florida," he wrote.

Trump's victory deals a heavy blow to Florida Sen. Marco Rubio, who had vowed to win his home state. With about two-thirds of the vote in shortly before 8 p.m., Trump was leading Rubio, 45.3% to 27.8%.

Though Rubio insisted earlier on Tuesday that he would soldier on even if he lost Florida, he had previously said the eventual nominee would be the candidate who won the Sunshine State. Rubio has thus far only won three contests: Minnesota, Washington DC, and Puerto Rico.

Winning Florida's 99 delegates also gives Trump a significant boost toward securing the nomination.

Trump entered Tuesday's race with 469 delegates, almost 100 greater than his closest competitor, Sen. Ted Cruz. The real-estate developer's victory will almost certainly widen his delegate lead and put him closer to clinching the 1,237 delegates needed to win the nomination.