Senior Republican Senator Lindsey Graham said reports that North Carolina Republican gubernatorial candidate Mark Robinson called himself a “black NAZI!” in posts on the porn forum Nude Africa a decade ago were “beyond disturbing” and, if proven true, would end his political career.

“If they are true, he is unfit for office,” the longtime senator from South Carolina said on Sunday. “If they are not true, he is facing the best defamation suit in the history of the country.”

Graham, however, did not demand that Robinson withdraw his candidacy for governor. Robinson has denied CNN's claim that the inflammatory posts on the forum were his own. Nor did he demand that Donald Trump, who has called Robinson “Martin Luther King on steroids,” withdraw his support for the candidate.

“I think what's going to happen here is he deserves a chance to defend himself,” Graham said. “He's claiming they were artificially created.”

Graham advised Robinson, who has made controversial and racist statements in the past, to “hire the best lawyer I can find. I would sue CNN because what they are saying about him is just unbelievable.”

Graham, however, said Robinson “needs to do more… he has a right to defend himself. He has a duty to defend himself. That hangs over his campaign.” However, he does not believe that the Trump protégé's comments “harmed Trump.”

“But Robinson is a political zombie unless he presents a credible defense,” Graham added.

Robinson's alleged comments on porn sites dominated Sunday talk shows across the U.S., a day after Trump held a rally for 10,000 supporters in North Carolina without mentioning Robinson or omitting the candidate's appearance on stage.

“Those are not my words and that's not something that's typical of me,” Robinson, North Carolina's first black lieutenant governor, said of the alleged posts. He has said he plans to stay in the race.

Robinson's opponent, former Attorney General Josh Stein, told CNN that his opponent's “vile insults” made him “completely unfit” for the office of governor.

“What he said in the posts is consistent with what he said publicly on Facebook,” Stein said. “He hugged Hitler, he complimented Hitler, he said he was a Nazi, he bought little toy SS soldiers, he insisted he wanted to reinstate slavery … things that defy imagination.”

One of Robinson's alleged comments on the website, written during Barack Obama's tenure in the White House, read: “I'd choose Hitler over any crap going on in Washington right now!” and “Slavery isn't bad. Some people have to be slaves. I wish they'd bring (slavery) back. I'd definitely buy a few.”

The controversy surrounding Robinson's alleged comments comes at a time when North Carolina, a typically red state, must be a win for Trump if he is to reach the 270 electoral votes needed to enter the White House.

Polls show Stein leading Robinson by about 10 percentage points on average, but the race is closer among the state's other Democratic candidates, including presidential candidate Kamala Harris.

It is unknown how much impact Robinson's alleged comments will have on Trump's support, but Democrats hope to link her to Republican campaigns at the local and national levels.

Anderson Clayton, chairman of the North Carolina Democratic Party, said Robinson was a “standard bearer” and there were signs that local Republicans would rally behind their candidate. “He represents their party … The rest of the Republican slate is just a rubber stamp for his agenda,” she said.

On Sunday, former New Jersey Governor Chris Christie told ABC This Week that controversy surrounding Robinson was “predictable” because Robinson's tenure in public life “has been consistently marked by erratic, sometimes highly offensive statements.”

But Christie acknowledged that this is a problem for Republicans because “since Donald Trump is your recruiting agent for candidates in the swing states, we're going to continue to get our butts kicked.”

Christie doubted other Republicans would be affected – a political concept known as “reverse coattailing.” Robinson, on the other hand, is “starting to get a sense of what it's like to have been a former friend of Donald Trump.”

He added: “From a political perspective, Donald Trump smells rotting flesh better than anyone you will ever find… And I bet you, George, that before November 5th he will claim he doesn't even know who Mark Robinson really is.”