Washington (CNN) Florida Rep. Patrick Murphy made his long-expected Florida Senate bid official on Monday morning, giving Democrats their preferred candidate in the race.

"I've spent the last several months considering the best way I can continue to serve the people of Florida, and today, after much thought and discussion with people from across this state, I'm proud to announce that I will be a candidate for the United States Senate in 2016," he said in a statement.

Murphy was openly contemplating a run and, in the clearest hint he was moving towards a bid, was spotted leaving a Democratic Senatorial Campaign Committee event last week, according to the Washington Post

Republican Sen. Marco Rubio is expected to launch a presidential bid in the coming months, but he hasn't yet made those plans official, and Murphy framed his bid as a challenge to the incumbent — but hinted at Rubio's ambition — in his statement.

"For years, Senator Rubio has put the needs of Floridians behind his presidential ambitions. We need a leader in the Senate whose eyes are firmly fixed on the people of Florida by working together to get things done," he said.

Read More