The rocky relationship between Gov. Brian Kemp and Donald Trump hit a new low on Sunday when the president said he was “ashamed” that he endorsed the fellow Republican in a tight race for governor in 2018.

“The governor has done nothing,” Trump said during a Fox News interview on his false claims of rampant voter fraud in Georgia. “He’s done absolutely nothing. I’m ashamed that I endorsed him.”

The remarks came as the president vented that neither Kemp nor Secretary of State Brad Raffensperger, another Republican he supported in the midterm, prevented the certification of results that showed he narrowly lost the state to Joe Biden.

The criticism marks the nadir of a partnership between Kemp and Trump that has steadily deteriorated since the governor tapped Kelly Loeffler to an open U.S. Senate seat over the president’s favored pick of Doug Collins.

It further highlights the fractious Republican infighting in Georgia ahead of Jan. 5 runoffs that will decide control of the U.S. Senate, and the tricky position it puts GOP officials who are wary of antagonizing him or his loyal base of supporters.

And the swipe could haunt Kemp through the 2022 midterms, when he is gearing up to face Stacey Abrams in a likely rematch. It appears increasingly possible that he might first have to survive a primary challenge from a Trump-backed adversary — perhaps Collins, a four-term congressman now leading the president’s Georgia recount effort.

The outpouring of anger has been one-sided: Each time Trump has swiped at the governor, he’s either declined to respond or turned to a common enemy, such as Democrats or the media. Still, state GOP officials say the president seems to have taken Kemp’s decision to sign off on the certification of the election as a personal betrayal.

Trump has often taken credit for Kemp’s narrow 2018 defeat of Abrams. His surprise endorsement of the Republican six days before a runoff contest against then-Lt. Gov. Casey Cagle helped turn what was already likely to be a Kemp victory into a runaway rout.

And he visited three days before the general election to energize Republicans with claims that Abrams would make “neighborhoods unsafe and make your jobs disappear like magic” if she won. A vote for Kemp, he told a crowd of thousands of GOP faithful, was the same as a vote for him.

November 4, 2018 Macon - GOP gubernatorial candidate Brian Kemp speaks as President Donald J. Trump looks during President Donald J. Trump’s Make America Great Again Rally to support Brian Kemp at Middle Georgia Regional Airport in MaconSunday, November 4, 2018. HYOSUB SHIN / HSHIN@AJC.COM

HYOSUB SHIN / AJC

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HYOSUB SHIN / AJC

But soon there were signs of fissures between the two Republicans. Shortly after he took office, Kemp appealed to Trump to free up Hurricane Michael relief that stalled in Congress for months. And he went against Trump’s wishes by picking Loeffler for the seat held by retiring U.S. Sen. Johnny Isakson.

The next major flashpoint came in April, when Trump sharply opposed Kemp’s plan to start reopening Georgia’s economy during the pandemic. He said repeatedly he “totally disagreed” with Kemp’s decision before later falsely asserting he never criticized Kemp.

As the November election neared, Kemp encouraged Trump and national Republicans to pay heed to polls showing a tight race in a state Republicans held in every White House race since 1996, and openly talked of Georgia as a “battleground.”

After his defeat in Georgia, Trump intensified claims of widespread irregularities at the polls — allegations that Raffensperger and other GOP officials consistently refuted.

While some Republican leaders echoed Trump’s broadsides against Raffensperger — Loeffler and U.S. Sen. David Perdue both called on him to resign — Kemp was more limited in his critique.

And he refused Trump’s overtures, on social media and in a phone call, to more loudly amplify the president’s unsubstantiated claims of a “stolen” election. The governor, meanwhile, has stayed closer to Vice President Mike Pence, who has visited the state frequently throughout the year.

During his Fox News interview, Trump repeated allegations of widespread fraud in Georgia and called Raffensperger a “disaster.” Those attacks, along with Trump’s insistence the election was “rigged,” have unnerved Republicans worried they could dampen GOP turnout in the runoffs.

“I look at what’s going on — it’s so terrible. What happened in this election, Maria, I can’t imagine has ever happened before,” he said in his interview with Maria Bartiromo, claiming with no evidence that Democrats “stuffed the ballot boxes.”

Raffensperger has frequently fired back at Trump, poking fun at his tweets and accusing the president of authoring his own defeat by denigrating mail-in ballots. Kemp has taken a different tack. Though his office didn’t comment on Sunday, the governor has refrained from swiping at the president.

“I understand why he’s frustrated. He’s a fighter,” Kemp told The Atlanta Journal-Constitution shortly after he certified the state’s 16 Democratic electors. “But at the end of the day, I’ve got to follow the laws of the constitution of this state and that’s exactly what I’m doing.”