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MIAMI (CBSMiami) – When incumbent Senator Marco Rubio announced months ago, he would not seek re-election, several others set their sights on the Florida senator’s seat — including two politicians who already hold office on Capitol Hill.

Democrats Patrick Murphy and Alan Grayson are looking to make the move from the U.S. House of Representatives to the United States Senate.

Patrick Murphy is Florida’s 18th Congressional District representative to the House. He’s held that seat since 2013.

Primary Election 101: Absentee Ballots To Election Day

Murphy was first elected in 2012, defeating Republican incumbent Allen West in the most expensive U.S. House race in history. He was re-elected to his second term in 2014 with a whopping 60 percent of the vote.

Murphy even has the backing of President Barack Obama who appears in his latest campaign ads.

“We’re very excited about that endorsement. And there’s a very clear contrast between the two Democrats for sure in this race. And we’ve proven ourselves effective, capable of reaching across the aisle to solve problems,” said Murphy. “And you compare that to my opponent, the hedge fund manager in this race and there’s a very sharp contrast.”

That hedge fund manager is Alan Grayson who says Murphy takes every opportunity to discredit him.

“I had one reporter tell me he got five calls a day from Murphy flacks pushing negative stories against me,” said Grayson.

Related: Tough Times For Congressman Alan Grayson

Grayson is also the United States Representative for Florida’s 9th Congressional District. The Democrat previously served as the U.S. Representative for Florida’s 8th Congressional District from 2009 to 2011. He says he has endorsements of his own.

“Slade Magazine says I’m the most effective member of Congress. Time Magazine says I’m a standout member of Congress in a do-nothing Congress. Business Insider which is not exactly friendly to a Democrat like me, says that I am the most productive member of Congress,” said Grayson.

Related: Murphy Rejects Senate Debates With Grayson

Grayson was defeated in his re-election bid in 2010. When he ran again for Congress in 2012 for the newly created District 9 seat, he defeated his Republican challenger and was re-elected to his second term in that district in 2014. It was his third time in the U.S. House of Representatives.

A St. Petersburg poll released two weeks ago puts Murphy ahead with 45 percent compared to Grayson with 20 percent.

The Democrat who is victorious in the Florida Primary will face the winner of the Republican race where real estate developer Carlos Beruff will go head-to-head with Marco Rubio.

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