MIAMI (CBSMiami) – Republican Representative Connie Mack IV picked up several key Republican endorsements Monday in his battle to unseat incumbent Senator Bill Nelson.

Representatives Ileana Ros-Lehtinen, Mario Diaz-Balart, David Rivera and former Representative Lincoln Diaz-Dalart all endorsed Rep. Mack for the Republican nomination to take on Senator Nelson.

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Mack was a late addition to the Senate race, but immediately vaulted to the top of the Republican field which was weak at best. Mack’s declaration already moved Adam Hasner out of the Senate race and into a House race in South Florida.

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“I am truly honored to have earned the trust and support of Ileana Ros-Lehtinen, Mario Diaz-Balart, David Rivera and Lincoln Diaz-Balart. Florida is a better place because of their dedication to the people whom they represent and fight for every day,” Mack said.

Still, Mack faces an uphill battle against Senator Nelson.

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The Democrat enjoys a large fundraising lead over Mack and has not been tied too much to the Obama administration. This will be Mack’s target in the coming months, to chain Nelson to Obama and hope that Obama doesn’t have coattails in the fall.