Photo via Federal Bureau of Investigation (FBI)

The feud between former FBI Director James Comey and President Donald Trump reached new heights over the weekend.

During an interview with George Stephanopoulos for ABC’s 20/20 that aired Sunday night, Comey said that Trump did not possess the tools necessary to fulfill his duty as president.

“Our president must embody respect and adhere to the values that are at the core of this country,” Comey told Stephanopoulos. “The most important being truth. This president is not able to do that. He is morally unfit to be president.”

And as has become customary in the case of any high-profile slight against the president, Trump immediately took to Twitter, using his 280 characters to call Comey a “slimeball,” “slippery,’ and “the worst FBI Director in history.”

Before Comey was speaking out about Trump’s moral compass, however, he was blamed by some Democrats and political pundits as throwing the election in Trump’s favor, when he announced a decision to reopen an FBI investigation into Hillary Clinton’s email servers just days before the 2016 presidential election.

Once the election was over though, and whispers of Russian influence turned into a full-scale scandal, the relationship between Trump and his FBI chief quickly turned sour. In a story that Comey retold on 20/20 — one that Trump has denied for a year — the former FBI Director said that the president requested his “loyalty” at a dinner that Comey described as “like a mob initiation.”

Trump fired Comey in May 2017 after he refused to publicly declare that the president was not under investigation in relation to the Russian election tampering inquiries.

Since then, the two have gone back and forth in the media, culminating recently in the publishing of Comey’s tell-all memoir, “A Higher Loyalty: Truth, Lies, and Leadership.” Now on a publicity tour, Comey is deriding Trump at every turn, incurring even more of the president’s all-caps Twitter rampages.

After Comey’s 20/20 interview aired Sunday, Trump immediately began typing, accusing Comey of lying to Congress and leaking classified information.

“The big questions in Comey’s badly reviewed book aren’t answered like, how come he gave up Classified Information (jail), why did he lie to Congress (jail), why did the DNC refuse to give Server to the FBI (why didn’t they TAKE it), why the phony memos, McCabe’s $700,000 & more?” Trump tweeted.

In Sunday’s interview, Comey also levied some insults about Trump’s personal stature and features.

“His tie was too long, as it always is,” Comey told Stephanopoulos. “He looked slightly orange up close with small white half-moons under his eyes, which I assume are from tanning goggles.”

It is still not clear what, if anything, will actually come from this political beef besides more name-calling and mud-slinging. But both in his book and on Sunday’s 20/20 interview, Comey said that in February 2017, Trump pulled him aside and asked him not to investigate his recently fired National Security Advisor Michael Flynn. As Robert Mueller’s investigation into Russia’s role in the 2016 election continues, pundits predict that any legal action against Trump would be an obstruction of justice charge corroborated by Comey’s testimony about the Flynn investigation.

For now, though, the feud is nothing but a war of words that appears to be escalating by the day. And while Comey has not responded to Trump’s outrage Sunday night, the president did not appear to regain any composure after the weekend, firing another jab at Comey from his Twitter account Monday morning.

“Comey drafted the Crooked Hillary exoneration long before he talked to her (lied in Congress to Senator G), then based his decisions on her poll numbers. Disgruntled, he, McCabe, and the others, committed many crimes!” Trump tweeted.