Florida Gov. Rick Scott, in conversations with major Republican donors over the past week, has signaled that he is moving closer to challenging Sen. Bill Nelson and has mapped out financial and political plans that could guide his potential bid, according to three people familiar with the discussions.

Scott’s study of the race’s dynamics and his confidence that the veteran Democrat is vulnerable has led those donors to conclude that the governor is now leaning toward running, the people said, requesting anonymity to discuss private exchanges.

“He thinks Nelson isn’t ready for the velocity of a 2018 campaign,” according to one person who has spoken with Scott in recent days, describing the governor as a data-obsessed former businessman.

A potential Scott and Nelson race could be a nail-biter in a state President Trump narrowly won in 2016. Senate Republicans, who hold a razor-thin 51-49 majority, see Florida as a pickup opportunity as they look to boost their numbers in what could be a tough year for the president’s party.

President Trump praises rapid response to Irma in Florida on Sept. 14 and endorsed the governor's possible Senate run. (The Washington Post)

Scott has spoken at length with donors about fundraising, the state’s media markets and the differences between running for Senate and governor, the person added.

Scott has told donors that his possible Senate campaign would likely need more than $100 million to succeed — a total close to the amount he has spent in each of his gubernatorial races, the people said. The multimillionaire, who has self-funded past campaigns, has also made clear that he would count on donors outside of Florida — not just his fortune and Florida donors — if he were to help the GOP by getting into a tough Senate race, they added.

Over the past week, Scott has met with Republican donors out West before quickly returning to Florida on Wednesday following the mass shooting that killed 17 people at Marjory Stoneman Douglas High School in Parkland, Fla.

Trump, White House aides and Republican leaders have long sought a Senate bid by Scott as they are eager to land a high-profile recruit amid rising unease in the party about the 2018 midterm elections.

A Republican close to Senate Majority Leader Mitch McConnell (R-Ky.) said Thursday they believe Scott is looking at jumping in at some point after Florida’s legislative session ends in early March, but have not received a firm answer from him.

Both publicly and privately, Scott insists that he remains undecided at this time.

Curt Anderson, a longtime Scott political adviser, said Thursday that any decision will be Scott’s alone and not based on entreaties from donors or Republican leaders — even the president.

“He’s unrecruitable,” Anderson said. “He’s not a career politician looking at the next thing to run for. It’s nice that people want him to run, but he doesn’t take that into account, especially the people in Washington. They’ve gotten the hint.”

When asked about Scott’s lengthy chats with donors about his metrics for a Senate campaign, Anderson said, “He applies metrics to all decisions, whether it’s tourism, job growth, or campaigns. And he probably applies metrics to what’s for lunch, too.”

Recent polls show a potentially close race between Scott, 65, and Nelson, 75, who was elected to the Senate in 2000.

A Mason-Dixon survey earlier this month showed Nelson with 45 percent support, Scott with 44 percent. A University of North Florida poll had Nelson with a slightly stronger edge, 48 percent to Scott’s 42 percent.