President-elect Donald Trump will no longer be using his "drain the swamp" slogan said one of his closes advisers, Republican Newt Gingrich, on Wednesday.

"I'm told he now just disclaims that. He now says it was cute, but he doesn't want to use it anymore," Gingrich said of Trump's iconic campaign slogan while speaking with NPR radio's "Morning Edition" 21 December.

Trump used the phrase throughout the later days of his campaign to describe how he would clean up corruption and money in American politics if voters elected him to America's highest office.

Trump first used the slogan in a tweet on 18 October. "I will Make Our Government Honest Again -- believe me. But first, I'm going to have to #DrainTheSwamp in DC," he wrote.

He used the slogan on the social media platform nearly 40 times afterward. He first said it at a campaign rally the same day in Colorado where he also described Washington DC as a toilet that needs flushing.

Gingrich, a former House Speaker, said that he recently wrote a tweet about Washington stalwarts – who he referred to as "alligators" – complaining about Trump's efforts to root out corruption.

"Somebody wrote back and said they were tired of hearing this stuff," Gingrich told NPR. However, there is no evidence on his Twitter profile that such a response ever happened.

"I've noticed on a couple of fronts, like people chanting 'lock her up,' that he's in a different role now and maybe he feels that as president, as the next president of the United States, that he should be marginally more dignified than talking about alligators in swamps," said Gingrich, who owns the firm Gingrich Communications.

Gingrich said that despite his support for the "drain the swamp" slogan, he is ready to follow Trump. "He is my leader and if he decides to drop the swamp and the alligator I will drop the swamp and the alligator," he said.

Trump has faced a number of questions about conflicts of interest between governing and his business interests since being elected 8 November. On Tuesday (20 December) Trump's children had to drop an event that for $500,000 to $1 million would give a donor access to Trump the day after his inauguration and a hunting trip with his sons, Donald Trump Jr and Eric Trump. A 45-minute meeting with Trump's daughter Ivanka, at a cost of $72,888, was also cancelled.

Trump also cancelled a press conference he had scheduled for 15 December in which he said he would explain how he would divest himself of his business interests.

On 30 November he explained that "legal documents are being crafted which take me completely out of business operations," adding he thought it "visually important, as President, to in no way have a conflict of interest with my various businesses." These arrangements have not yet come to light.

Yet Trump should deal with his business holdings ahead of his inauguration on 20 January next year, Gingrich said. Trump "has to understand and his family has to understand that there is a public interest which transcends them," he said.

Yet he added that Trump is a special case. "At the same time, we have to understand that this is a new situation we've never seen before," Gingrich said, "and the rules [that] were written for people who were dramatically less successful literally do not work."