It’s known in Iowa as the “Full Grassley” — visiting all 99 of the state’s counties ahead of an election — and it’s considered both a test of endurance and of commitment to getting to know Hawkeye voters.

Florida Gov. Ron DeSantis is about to become the latest to accomplish the feat when he checks off his final county this weekend, as he battles for the state’s nod in the GOP 2024 presidential race.

“The Republican winners of the last three Iowa caucuses all completed the ‘Full Grassley’ because they knew Iowans expect their candidates to show up and earn their support,” said DeSantis spokesman Andrew Romeo. “Winning an Iowa caucus requires a strong combination of outworking and out-organizing the competition and that’s been the Ron DeSantis model.”

“This historic milestone is just another example of how no one in the race is coming close to matching Ron DeSantis as we hit the deciding stretch,” he said.

Indeed, history suggests it’s a good way to connect with Iowa voters. The winners of the Iowa Caucuses in 2008, 2012 and 2016 all completed the Full Grassley — but none went on to win the Republican nomination itself.

“The ‘Full Grassley’ is a nice publicity stunt, but it’s neither necessary nor sufficient for electoral success,” said Dennis Goldford, a political science professor at Drake University in Des Moines.

Named after the state’s legendary long-serving Sen. Charles E. Grassley, who has done the 99 counties every year for the past 43 years, the feat has become a way for national candidates to prove to Iowa that they value the state and its early role in the nominating process.

Now 90 years old, Mr. Grassley completed this year’s tour in August. He says it’s a way to hold himself accountable and keep in touch with his constituents.

“From flat tires and empty gas tanks to icy roads, speeding tickets, and yes, deer in the headlights, I’ve enjoyed every minute of every mile,” Mr. Grassley wrote in a 2020 op-ed for The Des Moines Register in which he said even the challenges from the coronavirus pandemic would not stop him.

Presidential hopefuls want the publicity that comes with completing the Full Grassley, as well as the contact with voters.

Sen. Ted Cruz of Texas did the Full Grassley in 2016, en route to winning the Iowa Caucuses. So did former Sen. Rick Santorum of Pennsylvania in 2012, and former Arkansas Gov. Mike Huckabee in 2008.

None of them, however, would win the GOP’s nomination.

“I am confident in saying that no person elected as president traveled to all 99 counties in that election cycle,” said Ralph Brown, an attorney in Dallas County who has been active in Iowa Republican politics for decades, including stints as executive director and general counsel of the Iowa GOP.

That’s at least partly because the caucuses have become a bad predictor of the eventual winner.

George W. Bush was the last Republican to win the caucuses and become president, but he was an infrequent Iowa visitor.

This time around, former President Donald Trump has visited just 11 of the state’s 99 counties, according to a running tally from The Des Moines Register that shows after a pair of campaign stops Saturday he will have held 15 events in the state.

Mr. DeSantis has held 130 events in Iowa, according to his campaign.

Mr. Trump still has a 30-point lead in Iowa over his closest rivals, Mr. DeSantis and former U.S. Ambassador to the U.N. Nikki Haley.

Mr. Santorum said completing the Full Grassley shows a candidate believes “the state of Iowa is important, and you want to hear from them and that you are committed to being accessible to voters.”

“That, to me, is the biggest thing,” he told The Washington Times, adding that visiting all the countries is “just the beginning” of proving to Iowans you are authentic and truly care about them.

Mr. Santorum said he held around 385 events before the 2012 caucus and recalled having days where he held upwards of 9 events.

“If you’re just going there and checking a box to say, I’ve been to a county, so you can say I did the full Grassley?” he said. “Yeah, that’s a little different than sort of committing to the state.”

David Yepsen, a renowned Iowa political reporter who covered the caucuses for decades, said Mr. DeSantis has nothing to lose from pulling off the Full Grassley because it sends an “important symbol that signals to rural voters you care about them.”

“Many in rural America feel overlooked or ignored,” Mr. Yepsen said. “If a presidential candidate has time, there’s nothing wrong with doing one but it’s a huge investment of time.”

“For a guy like Desantis, who is in a do-or-die position here, it’s probably worth it to dig up every vote you can find,” Mr. Yepsen said.

But there are clear ceilings to its value.

Ryan Binkley, a little-known Republican candidate in the 2024 race, has already completed the 99-county tour.

“Does anyone seriously think that’s going to make him a real, let alone viable, candidate for the presidency?” Mr. Goldford said.

The DeSantis campaign plans to celebrate his 99 county triumph at a campaign rally featuring Iowa Gov. Kim Reynolds, Christian conservative activist Bob Vander Plaats and Iowa House Majority Leader Matt Winschitl.

The Trump campaign is downplaying Mr. DeSantis‘ accomplishment, saying the fact that Mr. Binkley beat him to the punch proves it’s not unique.

“As with his entire campaign, DeSantis is trying to gaslight voters and caucus-goers into believing he actually has a shot of becoming president,” the campaign said.

Mr. Binkley, a lead pastor of a Christian Church in Texas, thanked the Trump campaign for reminding the political universe he was the first to climb the every-county mountain.

“The time and energy I put into Iowa is the best investment I have made,” he said. “Meeting voters and hearing how my message resonates with them is the greatest return.”

Mr. Binkley is polling at zero percent and failed to qualify for the first three presidential debates.

Mr. Santorum, like others in the party, is convinced that Mr. DeSantis‘s chances of upending Mr. Trump in the primary contests hinge on a win — or at least a strong showing — in the Iowa caucuses, where religious and social conservatives play an oversized role.

“If I were that campaign, it is Iowa or bust,” he said. “If I was DeSantis I wouldn’t leave the state other than to raise money.”

• Seth McLaughlin can be reached at smclaughlin@washingtontimes.com.