A Florida Republican who was defeated by 59 percentage points in a congressional special election won't concede

• The Republican Jason Mariner hasn't conceded in Florida's 20th District special election House race.
• Sheila Cherfilus-McCormick, a progressive Democrat, beat Mariner in a 79%-20% landslide.

A Florida Republican who last Tuesday lost a congressional special election by a landslide in a heavily Democratic district has declined to concede the race, according to CBS Miami.

Sheila Cherfilus-McCormick — a Democrat who pledged to fight for $1,000 monthly checks for Americans and who backs progressive policies such as the Green New Deal and "Medicare for All" — easily defeated the Republican Jason Mariner in the race to succeed the Rep. Alcee Hastings, who died in April.

With all precincts reporting, Cherfilus-McCormick defeated Mariner 78.7% to 19.6% in Florida's 20th District — a 59.1-percentage-point victory. She received 43,663 votes to her opponent's 10,883 votes.

But in a move reminiscent of former President Donald Trump, who continues to dispute his election loss to President Joe Biden, Mariner has made claims of irregularities in the South Florida district.

"Now they called the race — I did not win, so they say, but that does not mean that they lost either, it does not mean that we lost," the Republican told CBS after the race was called.

Before the polls closed for the special election, Mariner filed a lawsuit alleging ballot issues in Broward and Palm Beach counties, the two populous Democratic-leaning jurisdictions that anchor the district.

"We'll also have some stuff coming out that we've recently discovered," Mariner told the TV station without elaborating.

Cherfilus-McCormick — who eked by Dale Holness by five votes in a multicandidate Democratic primary in November — brushed off Mariner's actions.

"Well, this wouldn't be my first time running against an opponent who is refusing to concede, so it's not our first time, and at the end of the day nothing can stop the motion," she told CBS.

Holness, a former Broward County commissioner, filed a lawsuit in November seeking to invalidate the Democratic primary results, alleging that Cherfilus-McCormick's advocacy for universal basic income was tantamount to bribing voters.

Election officials in Broward and Palm Beach counties told CBS the election results would be certified in 14 days — with challenges permitted for 10 days after that point.

While candidates who are unsuccessful in their races aren't legally bound to formally concede, Trump's continued refusal to acknowledge his 2020 loss despite a clear 306-232 Electoral College victory for Biden has morphed into a major point of contention for partisans, from the grassroots level to the halls of Congress.

In the wake of Trump's defeat in 2020, Republicans across the US have raced to implement voting restrictions, fueled by Trump's widely debunked claims of mass voter fraud.

Congressional Democrats have sought to nullify many of the provisions of Republican-authored election laws with the Freedom to Vote Act and the John Lewis Voting Rights Advancement Act but have been stymied nearly unanimous GOP opposition to the bills as well as by resistance from Sens. Joe Manchin of West Virginia and Kyrsten Sinema of Arizona to changing the filibuster.