Rubio defeated wealthy businessman Carlos Beruff, who spent more than $8 million of his own money on his campaign. With 96 percent of the vote in, Rubio had 72 percent to Beruff's 19 percent, The Associated Press reported.

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Congratulating @marcorubio on winning the Florida Senate GOP Nomination. pic.twitter.com/9aIoXumpDv — Mike Pence (@mike_pence) August 31, 2016

Rubio had promised during his presidential run that he would retire from the Senate. But he made a last-minute decision in late June to run for reelection.

The GOP field of challengers mostly cleared when Rubio made his announcement. Reps. David Jolly and Ron DeSantis, Lt. Gov. Carlos Lopez-Cantara and businessman Todd Wilcox all ended their campaigns shortly after.

Rubio’s reelection will be critical for GOP hopes of keeping control of the Senate. Democrats need to flip five GOP seats — or four if they maintain control of the White House — to win control of the Senate.

Rubio goes into the fall election against Rep. Patrick Murphy with an edge. He has high name recognition after unsuccessfully running for president and has been enjoying a lead in most general election polls.

Updated 10:10 p.m.