Setting the stage for an expensive race that could help decide control of the Senate, Republican Gov. Rick Scott announced Monday that he's running to unseat Florida's Democratic Sen. Bill Nelson.

Scott, a friend and ally of President Donald Trump who is being term-limited out of office after eight years as governor, said he's now aiming for the Senate because “career politicians” have created gridlock and dysfunction in the federal government.

“Washington is a disaster,” said Scott, who called for congressional term limits during his brief campaign kickoff at an Orlando construction company. “We shouldn't be sending the same kind of people to Washington.”

Scott's entry poses a formidable challenge to Nelson, who has not had a serious challenge since winning his first term in 2000. Scott is a multimillionaire businessman whose popularity has climbed during his final months in office, despite his sometimes rocky relationship with the Republican-controlled Florida Legislature.

Trump won Florida in the presidential election two years ago, but President Barack Obama carried the state in the two previous elections. Scott edged out narrow victories in his two runs for governor, both of them amid a backlash to Obama.

Nelson, in a brief statement, said he is ready for Scott.

“I've always run every race like there's no tomorrow — regardless of my opponent,” Nelson said. “While it's clear that Rick Scott will say or do anything to get elected, I've always believed that if you just do the right thing, the politics will take care of itself.”

Scott sought Monday to portray himself an outsider, an image he burnished in 2010 while riding a Tea Party wave into the governor's office. He predicted then that lobbyists would be “crying in their cocktails” once he won, but later obtained the support of the lobbyists and business interests that opposed his initial run.

Democrats have been anticipating Scott's campaign for months and have ramped up their criticism, noting that Scott was forced out as chief executive of Columbia/HCA amid a federal fraud investigation. Although Scott was never charged with any wrongdoing, the health care conglomerate paid a then-record $1.7 billion fine for Medicare fraud.

Democrats also plan to fault Scott over his wealth and his record while governor, including his initial push for deep budget cuts to education and his back-and-forth position on whether to expand Medicaid.

“Floridians will have the benefit of a clear-eyed view of a truly dismal record,” said Dan Gelber, a former state senator and now Miami Beach mayor. “Floridians won't forget the damage Rick Scott's self-serving politics have done these last seven years, no matter how he tries to change his spots and obscure his record.”

Scott's record on gun laws earned him an A+ rating from the National Rifle Association before the killings of 17 people at a Florida high school this year. Ultimately, Scott signed Florida's new law raising the age limit to purchase rifles to 21 and creating a new process enabling law-enforcement to seize guns from someone who is considered a danger.

Scott took aim at Nelson meanwhile, contending the Democrat has “done nothing” in the Senate on high-profile issues such as gun violence. Nelson said Scott has not done enough — he wants universal background checks and a ban on certain types of semi-automatic rifles.

Nelson, who talks with a Southern accent, began his political career in the era when Democrats controlled Florida government. He flew on a space shuttle as a member of Congress, and was elected as Florida's insurance commissioner before running for the Senate. His only notable election loss came in 1990 when he lost a Democratic primary for governor.

When Scott first entered politics, he appeared anxious with crowds and was an awkward speaker. Now, he's much more relaxed and self-assured. “I will bust my butt to win this election,” he said.

Gary Fineout reports for the Associated Press.