WASHINGTON (REUTERS) - US President Donald Trump said on Sunday (July 28) he would nominate Representative John Ratcliffe, a Republican who strongly defended him at a recent congressional hearing, to replace Dan Coats as the US spy chief.

Coats, the current US director of national intelligence who has clashed with Trump over assessments involving Russia, Iran and North Korea, will step down on Aug. 15, the president said on Twitter.

"I am pleased to announce that highly respected Congressman John Ratcliffe of Texas will be nominated by me to be the Director of National Intelligence," Trump said.

"A former US Attorney, John will lead and inspire greatness for the Country he loves," Trump added, thanking Coats "for his great service to our Country" and saying that an acting director will be named shortly.

The post of director of national intelligence, created after the Sept 11, 2001 attacks on the United States, oversees the 17 US civilian and military intelligence agencies, including the Central Intelligence Agency.

Ratcliffe, a member of the House of Representatives intelligence and judiciary committees, defended Trump during former Special Counsel Robert Mueller's testimony on Wednesday about his two-year investigation of Russian interference in the 2016 presidential election and possible obstruction of justice.

Ratcliffe also accused Mueller of exceeding his authority in the report's extensive discussion of potential obstruction of justice by Trump after the special counsel decided not to draw a conclusion on whether Trump committed a crime.

The congressman agreed that Trump was not above the law, but said the president should not be "below the law" either. Ratcliffe has served in Congress since 2015.

Before coming to Congress, he served as mayor for Heath, Texas, near Dallas, and as a US attorney. His congressional biography highlights his role as a prosecutor of terrorism cases and says he "arrested 300 illegal aliens in a single day."