As an intense, unforgettable end to September in the U.S. Senate spills over into October, it is a reminder of where Sen. Bill Nelson is likely to spend much of the final weeks of campaign season: In Washington.

Typically, Senators are freed of their D.C. work by now to stump back home. But the high-stakes nomination of U.S. Circuit Judge Brett Kavanaugh to the U.S. Supreme Court has required that senators remain in the nation's capital through every twist and turn in the confirmation process.

And Democrats expect Majority Leader Mitch McConnell will keep the chamber in session for most of, if not all of October, meaning Senators in difficult reelection battles, like Nelson, will have precious few days to stump in their home states.

Already, Nelson has maintained a lighter campaign schedule this election cycle than some Democrats are comfortable with. Like many of his Democratic colleagues in tight races, Nelson's time in the state has been largely relegated to weekends.

"I'm sure that some opportunities were missed; opportunities are always missed," said Dave Jacobsen, president of the North Florida Democratic Club. "I'm a believer of getting out and pressing the flesh and I've always encouraged them to be out with the grassroots people to energize them."

Nelson was remarkably quiet during the summer, when much of the state was focused on two highly anticipated primaries for governor. It allowed his Republican challenger, Gov. Rick Scott, to go untested on the airwaves, even as he faced critical coverage from a broken SunPass system, a confusing and controversial private beach access law and blue-green algae blooms in south central Florida.

After the primary, Nelson finally aired his first television ads and he'll remain on the air through the election. Despite facing tens of millions of dollars in attack ads, he is neck-and-neck with Scott, if not slightly ahead.

"A lot of us sat back during the summer and said hopefully there's a strategy," St. Petersburg Mayor Rick Kriseman said. "And I think now we're seeing that they have one and it's working."

Nelson and Scott take part in the first debate of the U.S. Senate race on Tuesday. The hour-long debate will be broadcast by Telemundo's stations in Miami, Fort Myers, Orlando, Tampa, West Palm and Orlando. It's the biggest moment yet in a race that could determine which party controls the U.S. Senate.

Longtime Nelson adviser Dan McLaughlin said the campaign has had to pick its shots against an opponent who has seemingly unlimited finances.

"You only throw your punches when you need them and at the right time," McLaughlin said. "And in this instance, I think Rick Scott's knees are buckling and it's the perfect time."

But Nelson's limited time on the trail has left him vulnerable to attack from Scott, who has spent the final months of his term in all-out campaign mode. He recently wrapped up a 10-day bus tour where he visited businesses and cities across the state.

"While Rick Scott travels the state talking to real Floridians about the issues that matter to them, Bill Nelson is nowhere to be found," Scott spokesman Chris Hartline said.

Nelson's campaign insists that the three-term Senator has spent ample time in the state despite McConnell's restrictive schedule. They have packed the weekends with campaign events. On Sept. 22, for example, Nelson spoke at an event marking the one-year anniversary of Hurricane Maria in South Florida and that evening attended a meeting of the Pinellas County Democrats Executive Club.

Nelson has also returned to the state on senate business, like on Sept. 10, when he unveiled legislation in Orlando and Tampa allowing veterans to use medical marijuana.

Democrats have accused McConnell of setting a schedule intended to make it difficult for them to campaign. Of the 35 senate seats up for election in November, 26 are held by Democrats, some of whom are in the most contentious races.

Still, the campaign must go on. Missouri Sen. Claire McCaskill, a Democrat running for re-election in a state easily carried by President Donald Trump, toured the state in an RV during a short reprieve in the Senate calendar in May. More recently, she has made the traditional campaign stops expected this time of year, at a restaurant and a college campus.

Sen. Joe Manchin, a West Virginia Democrat, deployed a surrogate to hold two town halls on Medicare and Social Security last week in his place.

"Please note, Manchin will not be in attendance for these events," the press release was sure to affirm.

Meanwhile, Republican Sen. Ted Cruz has made the decision to skip Senate votes and spend more time in Texas to stave off an unexpectedly tough challenge from Democrat Beto O'Rourke. Cruz has missed 23 Senate votes this year, including 13 in the last three months, more than almost any other Senator.

Nelson has missed 13 votes since January. That's more than the seven other Democrats running in the tightest contests, none of whom have missed more than four.

Five of those missed votes came on days when Nelson was working in the state, like when he was in Homestead at a detention facility raising awareness of Trump's family separation policies. That day, June 19, Nelson missed two lopsided, bipartisan votes.

Other votes were closer. On July 30, Nelson wasn't in the chamber for a 52-44 decision to end debate on a U.S. Circuit Court nomination.

McLaughlin noted Nelson still made 94 percent of his votes over that stretch, where as Scott "has a blank calendar on 54 percent of his work days," referring to a recent report that showed the governor's official calendar was blank most days this year.

In Lakeland this week, Scott said he is constantly meeting with people even if it's not on his calendar.

"I'm traveling around the state," Scott said, "but Bill Nelson isn't showing up."

Times Senior News Researcher Caryn Baird contributed to this report. Contact Steve Contorno at scontorno@tampabay.com.