Former U.S. Sen. Bob Graham said Wednesday in Naples that he expects a "very contested" race for Florida governor.

Former congresswoman Gwen Graham, Graham's daughter, lost the Democratic primary for governor to Tallahassee Mayor Andrew Gillum in a historic upset. Gillum faces Republican Ron DeSantis, who resigned from Congress this week to focus on his campaign.

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“I was disappointed. I thought that my daughter Gwen was well prepared to be the next governor of Florida, and I frankly thought she would be the next governor,” said Graham, who also was Florida's 38th governor before being elected to the Senate. “But it didn’t happen, and now I think we’re going to have a very contested general election.”

Graham, who spoke to the Greater Naples Chamber of Commerce at a breakfast meeting Wednesday, said he is supporting Gillum to become Florida’s first Democratic governor in almost two decades.

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“I think he brings fresh ideas,” Graham said. “He’s going to be challenged to build a coalition in Florida to get some of the things that we need to do, such as protect our water supply.”

Voters' choices of Gillum and DeSantis, who was endorsed by President Donald Trump, are an indication of the state's — and to a larger extent, the nation's — political polarization, Graham said.

“Of the Republican candidates, the most conservative was selected to be its candidate and on the Democratic side, the most liberal. That’s going to make it more difficult to find that middle ground that will actually move us forward," Graham said.

Graham also gave his support to U.S. Sen. Bill Nelson, who is facing a challenge from Gov. Rick Scott in what has become one of the nation's most closely watched midterm races.

Florida’s midterm election will play a key role in the Democrats' attempt to regain control of Congress, and Graham is optimistic that they’ll be successful, at least to some degree.

"I think there will be some (blue) wave," he said. "Whether it will be a tsunami or a relatively minor one is the question.”

That wave won’t happen, however, unless the younger generations start to get involved and use their voices, and votes, to make a difference, he said.

“Democracy gives power to individual citizens," he said. "What concerns me most is that we're not using that power, and I think it starts in the classroom, where young Americans learn to recognize the power that they have.

"You don't become a good tennis player by watching," he added. "You become a good tennis player by playing tennis."

In his new book, “America, the Owner's Manual: You Can Fight City Hall — and Win,” Graham gives advice to those looking to "play the game," with a particular emphasis on playing at the local level.

"The purpose of the book is to provide people with the means of gaining the skills that they can then apply," he said. "And it doesn't have to be things that are of national scope. In fact, I believe that the most important demonstrations of democracy are those that are held at the local level."

One such local issue is water quality, Graham said. For nearly a year a toxic red tide algal bloom has plagued the west coast of Florida, and now blue-green algae has crept into the state's freshwater rivers and canals.

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Collier County residents have already taken the type of action that Graham commends. Grass-roots organization Collier Clean Water is collecting signatures on two petitions that ask Naples and the county to pass "common sense fertilizer ordinances with higher standards than the state's model and with standards higher than the current ordinance(s)."

That level of citizen engagement, combined with the support of government officials, is what's going to fix Florida's water quality crisis, Graham said.

“I think that the issue for America for the next decade is going to be water, and Florida is the microcosm," he said. “I think it’s going to be imperative that the state, local government(s) and citizens collaborate with an intensity that we haven’t seen in years to reverse those threats that we see in our water supply."

Graham shared one of his favorite quotes from Robert Hutchins, University of Chicago chancellor from 1945 to 1951, to inspire Wednesday's crowd to get involved: "The death of democracy is not likely to be an assassination from ambush; it will be a slow extinction from apathy, indifference, and undernourishment."