Miami Herald reporter Joey Flechas is a co-author of this report.

MIAMI— U.S. Rep. Ron DeSantis submitted his resignation letter to House Speaker Paul Ryan on Monday, saying he was leaving Congress "effective immediately" to save taxpayers money while he campaigns for his next job.

"As the Republican nominee for Governor of Florida, it is clear to me that I will likely miss the vast majority of our remaining session days for this Congress," DeSantis wrote. "Under these circumstances, it would be inappropriate for me to accept a salary."

The letter asks that the resignation be retroactive to Sept. 1 so DeSantis is not paid for the month of September.

RELATED: The Buzz's Florida congressional vulnerability rankings, post-primary edition

Although Florida has a resign-to-run law that prohibits officials from holding two elected offices at once, DeSantis' move to leave Congress in the middle of the election is highly unusual, and hasn't happened in years. (In 2006, then-U.S. Rep. Mark Foley quit in September ahead of the November election after it was revealed that the Palm Beach County Republican had been sending sexually explicit messages to congressional pages.)

DeSantis was on his third term in Congress. Absent his resignation, he could have remained in office until the date his successor was sworn in, which will be on Jan. 3, 2019 — just days before Florida's next governor takes office on Jan. 8.

It has been an honor to serve the people of Florida's Sixth Congressional District. pic.twitter.com/j0SgILImyP — Ron DeSantis (@RepDeSantis) September 10, 2018

The decision is consistent with the strict ideology DeSantis has espoused as a Congressman. He declined to take part in the pension and health care plan shortly after he was elected in 2012. However, it could also indicate that he is feeling pressure from the campaign of rival gubernatorial candidate Andrew Gillum.

RELATED: Report: Ron DeSantis spoke at racially charged conference four times

Democrats pounced on the news, alleging that it was timed intentionally to "distract" from a Sunday night report from The Washington Post revealing DeSantis had spoken four times at a racially charged conference hosted by a right-wing activist who has tweeted that the "only serious race war" is against whites. A spokeswoman for DeSantis' congressional office, Elizabeth Fusick, has said he is not "responsible for the views and speeches of others."

"Ron DeSantis' entire political career has been about helping one person: Ron DeSantis," Florida Democratic Party Chairwoman Terrie Rizzo wrote in a statement. "Ron DeSantis can abandon his post, but he can't avoid questions about why he chose to associate himself with hateful, fringe organizations."

Gillum tweeted Monday evening that DeSantis' "actions and words are deeply troubling" but his campaign declined to comment further on the resignation.

During his three terms, DeSantis had a low absentee rate for most of his tenure representing the Palm Coast area. However, GovTrack, which tracks Congressional votes, shows that he missed 53.8 percent of his votes from July to September, a considerable spike.

Monday evening, DeSantis appeared in Miami's Little Havana neighborhood to formally launch his general election campaign with U.S. Sen. Marco Rubio and his pick for lieutenant governor, state Rep. Jeanette Nuñez, speaking to a packed room at the Bay of Pigs Museum and Library.

He addressed his abrupt resignation after his speech. He told reporters he was able to better juggle his role in Congress during the primary campaign, but when Congress was in session last week, he realized he couldn't split time between Florida and Washington anymore.

"There's just no way I could've gone. I had all this stuff," he said. "So I took an honest look at it and said look, if I'm going to be missing 70, 80 percent of the votes — not just before the election, because we're going to have a transition afterwards … Can I take a paycheck if I'm not really doing it?"

DeSantis also responded to the Post report, saying he "totally rejects" white supremacy, has "zero interest" in racial discrimination and called the story a "hit job." He also noted that at one of the conferences he attended, he spoke a day after Medal of Honor recipient Clinton Romesha delivered the keynote address.

"It's absurd," DeSantis said. "They're just trying to form a narrative."

DeSantis was a founding member of the House Freedom Caucus, a group of the most strident right-wing members of the U.S. House of Representatives, and has been one of Congress' loudest voices criticizing the special counsel investigating Russian collusion with the Trump campaign.

U.S. Rep. Matt Gaetz, the Fort Walton Beach Republican who has stumped with DeSantis and is one of his closest allies in Congress, said he feels like "Robin without Batman." He said he spoke to DeSantis about his resignation Monday morning.

"While Ron ran in the primary he was running against someone who had a government job who spent every day campaigning," Gaetz said. "He felt like it would have been hypocritical for doing what he criticized (Agriculture Commissioner) Adam Putnam for."

Added Gaetz: "Based on what I've been reading about Andrew Gillum, serving taxpayers over self may be foreign concept."

DeSantis' absence from Congress comes three weeks before lawmakers must pass a spending package to keep the federal government running past Sept. 30. DeSantis has typically bucked GOP leadership to vote down the proposals amid concerns of what he believes is out-of-control federal spending.

READ MORE: Defending Trump, threatening shutdowns: What 5 years in Congress tell us about Ron DeSantis.

President Trump has hinted that their might be a federal shutdown in October, though congressional Republicans are expected to at least pass a short-term spending bill to keep the government running during campaign season.

As of Monday, there are now six vacant seats in U.S. House whose constituents will have no representation until after the November election. DeSantis represented the 6th Congressional District, which runs from southern Jacksonville to New Smyrna Beach. Fusick did not respond to questions about whether DeSantis' district will still be offered constituent services such as help with Social Security checks.

Running to take over DeSantis' potentially vulnerable seat is Republican Mike Waltz, who bears many similarities to DeSantis as a former Green Beret, adviser to Dick Cheney and Fox News contributor. The Democrats have fielded Nancy Soderberg, a former ambassador to the United Nations and deputy national security adviser to President Bill Clinton, who easily won her primary.

McClatchy staff reporter Alex Daugherty contributed to this report. Emily L. Mahoney at emahoney@tampabay.com. Follow @mahoneysthename.