Moving Harris, who currently serves as commander of the US Pacific Command, was Mike Pompeo's idea of US Secretary of State, before possible talks between President Donald Trump and North Korea's leader Kim Jong Un, sources said.
A source told CNN that Pompeo has proposed the change waiting for Trump's blessing.
Harris' confirmation that he was ambassador to Australia was scheduled for Tuesday but has been postponed.
"At the request of the administration, the hearing was postponed to early May," said Micah Johnson, a spokeswoman for Senate Foreign Relations, Bob Corker.
While Seoul is arguably the most important diplomatic post with potential Kim Australia is also a "five-eye" information partner who needs a new ambassador to go through the validation process if Harris moves.
The White House did not immediately respond to CNN's request for comment.
During his tenure at Pacific Command, Harris has lost no words about North Korea's ambitions.
US forces in the Pacific "must be ready to fight tonight I take his word for it," he said last year about Kim's intentions. "I have to assume that his claims are true ̵
Harris has also watched as China itself in the Pacific, and has built a military presence on man-made islands in areas where the US and its allies are international waters  Harris graduated from the US Naval Academy in 1978 and was appointed Marine Officer after graduating other commandos in the navy, including the US Pacific Fleet and the 6th Fleet.
Sen. Robert Menendez, the top Democrat in the Senate Foreign Relations Committee, said on Tuesday that he had not been informed of any plans to relocate Harris to South Korea.
"I consider a candidate for South Korea incredibly important, and I & # 39; I must hear the Admiral's views on the whole challenge of the Korean Peninsula and denuclearization," Menendez said.
The Democrat from New Jersey added that it is important to have an ambassador to South Korea, but "Australia is also important as a Pacific ally."
In January, the Trump government decided not to nominate Victor Cha – a long-time candidate to be US ambassador to South Korea – a reversal, said CNN at the time being driven by a disagreement over a "bloody" nose "strike against Pyongyang.
Cha, a widely respected academic and former Bush administration official, said in a Washington Post earlier this year that the answer was The "real and unprecedented threats" of North Korea is not, as some Trump administration officials have suggested, a preventive military strike. "
Instead, Cha He set out what he called "a powerful military option that can tackle the threat without escalating into a war that would probably kill dozens, if not hundreds, of thousands of Americans."
South Korea is only one stay clear of dozens of important ambassadors.
CNNs Jamie Crawford, Elise Labott, and Nicole Gaouette contributed to this report