The opening act of what could be the most expensive U.S. Senate race of all time centered on Liberty City.

Two young black men were murdered in a housing development known as Pork 'n' Beans on April 8, and Sen. Bill Nelson and Gov. Rick Scott rushed to speak with local officials and lawmakers to understand what happened in a neighborhood that usually doesn't get much attention from statewide elected officials. The next day, Scott officially announced his long-rumored bid against Nelson, Florida's only statewide elected Democrat.

The political fate of two retirement-age white men running for the Senate could hinge on voters in neighborhoods like Liberty City, reliably Democratic-leaning areas that traditionally don't deliver high voter turnout in off-year elections. And getting more than 90 percent of black voters will be crucial for Nelson. In 2014, Scott won reelection by 66,000 votes and received support from 12 percent of black voters, enough to make a difference in a razor-thin victory.

Black Democrats warn that complacency from Nelson will spell his doom in November, like it did to Hillary Clinton in 2016, when she lost the state by about 113,000 votes.

It isn't enough for Nelson to simply present himself as not being Rick Scott or Donald Trump, they said.

"For Senator Nelson, he needs that sort of 'This is my moment' to define what [he] would like to see for Florida," said Dwight Bullard, an African-American former state senator and former chair of the Miami-Dade Democratic Party. "I would hope Senator Nelson would be bolder especially considering… Gov. Scott is now running for Senate and he's going to speak boldly about some very right-wing things and be unapologetic about tax rollbacks."

Bullard argued that the lack of a competitive Democratic primary in the Senate race doesn't mean that Nelson can forget about constituencies like black voters that tend to vote overwhelmingly for Democrats. Instead, the lack of a challenge from the left should gives more space for the longtime moderate to engage with the party's base.

"Looking at polling and seeing a numerical advantage means nothing if you're playing it too safe. That's the lesson he should take away form Secretary Clinton's run," Bullard said. "She chose to not be that, and as a result kind of sat on the sidelines when there were clear and distinct questions people had in terms of what her true vision for the country looked like."

State Rep. Roy Hardemon, who represents Liberty City in Tallahassee, said the shootings in his district are emblematic of larger economic pressures on his community that require solutions beyond gun-control measures, a political priority for Nelson after the Parkland shooting.

"It was my pleasure to meet him [Nelson] in the past week but I've never seen him in our community," Hardemon said. "We sat and we talked about the AR-15s and the AK-47s, but we didn't talk about the root cause of the issue as to why these kids are out there killing people."

Hardemon said running a campaign that focuses on demonizing the National Rifle Association at the expense of a coherent economic message for Florida's working class voters isn't the way to engage African-Americans. Hardemon, a first-term lawmaker, also added that he understands the challenges Nelson faces when campaigning in a large and diverse state, making the point that it's hard enough for him to equally represent Liberty City and majority white neighborhoods like Miami Shores in his district.

To energize black voters, Democrats said, Nelson must be willing to push for economic solutions to systemic poverty, and tout himself as an elder statesman in the mold of Ted Kennedy, the former Massachusetts senator who served for more than 40 years on Capitol Hill.

Rep. Alcee Hastings, the longest-serving African American member of Congress from Florida, said Nelson has done a good job of building up relationships within the community over the years, but Scott's ability to pump millions into the race means Nelson must run up the score in neighborhoods like Liberty City to win.

"Now he's confronted with the real reality with having a competitor where money is his cheapest commodity," Hastings said. "My advice to him was, don't you let a Sunday pass without you being around the state in some of the black churches, but I don't have to encourage him to do that because he has done that rather traditionally."

Nelson spent past the weekend fundraising in Florida with New Jersey Sen. Cory Booker, a potential 2020 presidential contender, and California Sen. Kamala Harris sent an email to supporters urging them to help Nelson shortly after Scott made his bid official. Booker and Harris are both black.

But Bullard and Hastings said a deep understanding of local issues and connections with African American groups like churches and sororities will help Nelson more than endorsements from black colleagues in Washington.

"Florida is a local state. When you're on the campus of Bethune-Cookman, that has more of an impact than an email from Senator Harris or a visit from Senator Booker," Bullard said, referring to the historically black university in Daytona Beach.

Scott's relentless messaging on jobs throughout his time in office, and his nearly 100 percent name ID in Florida, could spur a minority of black voters to vote for him, so Nelson will need to campaign hard to keep Scott's share of the black vote at around 5 percent. Scott's campaign didn't respond when asked how he plans to reach out to black voters.

Nelson said his Senate record speaks for itself, and the contrast between his record and Scott's. Also in his favor, he says, is the presence of a question on Florida's November ballot to allow most felons the right to vote after they're released from prison. The question, Nelson said, will get more African American voters out to the polls in a non-presidential election.

"I don't think I have to get them motivated," Nelson said. "Since so much of the prison population is African American I think what they see is this is a disenfranchisement of over a million people in the state of Florida, and I think that is going to be motivation not only for people who feel strongly on the issue, if you've been rehabbed and done your time you ought to get your rights back. I think it's going to be a motivator in the African American community."

Nelson also voted against the confirmation of Attorney General Jeff Sessions for his record on voting rights, a vote he can use on the trail when talking about civil rights issues in Florida.

Dan Smith, a University of Florida political science professor, said there are about 965,000 African American voters in Florida who voted in the 2016 election who were registered during the 2014 midterm elections. Of that group, about 61 percent voted in 2014. Smith said it will be important and cost-effective for the Nelson campaign to find and identify the nearly 375,000 registered African American voters who cast votes in the 2016 presidential election but not the 2014 midterm election, and get them to the polls.

On the other hand, identifying unregistered African-American voters is a "high-cost, low benefit strategy" Smith said. Increasing turnout among already registered voters who voted in 2016 but not 2014, along with the nearly 2 million voters in Florida who registered since the 2014 midterm election, will be important for both candidates, but particularly Nelson, since non-white voters tend to show in lower numbers in midterm elections.

And Hastings offered a warning for Nelson now that Scott is already spending millions on television ads.

"If he spends all of his money on television the way the Clintons did and spends less money on turnout, particularly in the African American community, then he's going to have a hard row to hoe."