WASHINGTON (AFP) - United States President Donald Trump hit back on Sunday (Sept 30) at suggestions that his administration is trying to "micromanage" the FBI investigation of controversial Supreme Court nominee Brett Kavanaugh, accusing opposition Democrats of being interested only in obstruction.

Mr Trump ordered the new FBI investigation into sexual assault allegations against Mr Kavanaugh last Friday (Sept 28), as the Senate delayed a final vote on his confirmation as the key ninth member of the Supreme Court.

"Wow! Just starting to hear the Democrats, who are only thinking Obstruct and Delay, are starting to put out the word that the 'time' and 'scope' of FBI looking into Judge Kavanaugh and witnesses is not enough," the President tweeted.

"Hello! For them, it will never be enough."

At a dramatic televised hearing last Thursday, university professor Christine Blasey Ford accused the judge of pinning her down and assaulting her in the 1980s. Mr Kavanaugh vigorously denied the allegations.

Trump administration officials appearing on television on Sunday said the terms of the Kavanaugh inquiry were set by the US Senate, not by the President, but confusion was rife as to the scope of the new investigation.

Both the New York Times and NBC News cited multiple sources last Saturday as saying the White House was limiting the witnesses the FBI could question during a one-week background check.

But Mr Trump subsequently insisted on Twitter that the FBI had "free rein" to pursue the matter as it saw fit.

"I want them to interview whoever they deem appropriate, at their discretion," the President tweeted late last Saturday.

'Very concerned'

The Times said the FBI would question four witnesses, according to two people familiar with the matter. The list, reportedly drafted by Senate Republicans, did not include former classmates who had contradicted Kavanaugh's testimony about the extent of his youthful drinking and partying.

In a tweet on Sunday, Times reporter Sheryl Gay Stolberg quoted Dr Ford's lawyer, Ms Debra Katz, as saying: "We have not heard from the FBI, despite repeated efforts to speak with them." NBC said the FBI was not being allowed to investigate claims by Ms Julie Swetnick, who has accused Mr Kavanaugh of sexual misconduct at drink-fuelled parties in his student days.

In a separate report on Sunday, NBC quoted a senior US official and a second source as saying the limits imposed by the White House on the inquiry remained in place, despite Mr Trump's tweet.

The bureau has, however, contacted Ms Deborah Ramirez, a Yale University classmate of Mr Kavanaugh's who said he was sexually aggressive towards her at a party, the Washington Post reported.

A Democratic member of the Judiciary Committee, Senator Amy Klobuchar, told CNN that she was "very concerned" by the reported White House constraints on the inquiry.

"The White House should not be allowed to micromanage an FBI investigation," she said.

"We have to allow them to go ahead," said spokesman Sarah Sanders, who insisted that the White House was staying "out of the way", but also said the inquiry should not be allowed to become a "total fishing expedition" by the FBI.

Asked on Fox News on Sunday whether the White House had given the FBI a list of permitted witnesses, she replied, "Not that I'm aware of."

"The White House isn't intervening, we are not micromanaging this process," she said.

Dr Ford's wrenching testimony last Thursday engendered expressions of deep sympathy from many viewers, and scores of women shared accounts on social media of having been victims of sexual aggression.

'I'm a victim'

The recent events also drew a stunning revelation Sunday from one of Mr Trump's own senior advisers, Ms Kellyanne Conway.

While discussing the case on CNN, she said "I feel very empathetic, frankly, towards victims of sexual assault and sexual harassment and rape."

Continuing after a brief, somber pause, she said, "I'm a victim of sexual assault."

But she then added that it was unfair to condemn Mr Kavanaugh for an alleged action 36 years ago that could not be confirmed.

While the White House has denied setting limits on the FBI inquiry, Mr Norman Eisen, who was special counsel for ethics under former president Barack Obama, tweeted that it would be highly unusual if it were to do so.

"I dealt with hundreds of these as WH Ethics Czar & it is malpractice for WH to rule out Swetnick, Yale boozing" and more, he tweeted.

"I call cover-up."