US INTELLIGENCE chiefs are making their most detailed and persuasive case yet to president-elect Donald Trump that Russia interfered in the political process.

Director of National Intelligence James Clapper, CIA director John Brennan, and FBI director James Comey are preparing to point to multiple motives for Moscow’s alleged meddling as they brief Trump on their classified report in New York.

President Barack Obama received a briefing on Thursday, and a declassified version of the report is expected to be released at some point.

Since winning the election, Trump has repeatedly questioned intelligence officials’ assessments that Russia was behind the hacking of the Democratic National Committee and individual Democrats like Hillary Clinton campaign chairman John Podesta.

He remained dubious about the assertion even on the eve of his intelligence briefing, asking how officials could be “so sure” about the hacking if they had not examined DNC servers.

“What is going on?” he wrote on Twitter.

A senior law enforcement official said the FBI stressed to DNC officials the importance of obtaining direct access to the servers “only to be rebuffed until well after the initial compromise had been mitigated”.

The official said the FBI had to rely on a “third party” for information, but did get access to the material it needed.

The Washington Post, citing anonymous US officials, has reported that intelligence agencies have identified parties who delivered stolen Democratic emails to WikiLeaks.

The officials also said there were disparities between efforts to infiltrate Democratic and Republican networks and said the US intercepted communications in which Russian officials celebrated Trump’s victory. It was not clear which of those details were included in the classified report.

Ahead of the briefing, Trump moved to fill out his own intelligence leadership team, tapping former Indiana Senator Dan Coats to lead the Office of the Director of National Intelligence, according to a person with knowledge of the decision.

Coats served as a member of the Senate Intelligence Committee before retiring from Congress last year.

If confirmed by the Senate, he would oversee the umbrella office created after the 9/11 attacks to improve co-ordination of US spy and law enforcement agencies.

Coats, a 73-year-old Capitol Hill veteran, served eight years in the House before moving to the Senate in 1989 to take Dan Quayle’s place when he became vice president. He stayed in the Senate until 1998, then left to become a lobbyist.

After a stint as ambassador to Germany under President George W Bush, he returned to Indiana for a Senate comeback bid in 2010. He did not seek re-election last year.

Coats was a harsh critic of Russia and pushed the Obama administration to punish Moscow for its annexation of Crimea in 2014.

When the White House levied sanctions, the Kremlin responded by banning several politicians, including Coats, from travelling to Russia.

Coats’ nomination is likely to quell concerns that the president-elect is seeking a sweeping overhaul of intelligence agencies.

Trump’s transition team has also been considering ways to restructure agencies to streamline operations and improve efficiency.