WASHINGTON — The FBI has received no new instructions from the White House about how to proceed with its weeklong investigation of sexual misconduct allegations against Supreme Court nominee Brett Kavanaugh, a senior U.S. official and another source familiar with the matter tell NBC News.

According to the sources, the president’s Saturday night tweet saying he wants the FBI to interview whoever agents deem appropriate has not changed the limits imposed by the White House counsel’s office on the FBI investigation — including a specific witness list that does not include Julie Swetnick, who has accused Kavanaugh of sexual misconduct in high school.

Also not on the list, the sources say, are former classmates who have contradicted Kavanaugh’s account of his college alcohol consumption, instead describing him as a frequent, heavy drinker. The FBI is also not authorized to interview high school classmates who could shed light on what some people have called untruths in Kavanaugh’s Senate Judiciary Committee testimony about alleged sexual references in his high school yearbook.

The sources said nothing would preclude the FBI from asking Kavanaugh's high school friend Mark Judge, who is on the witness list, about Swetnick’s allegations, but the sources stressed that this is not a top priority.

Separately, a White House official made clear that the White House is the client in this process. This is not an FBI criminal investigation — it is a background investigation in which the FBI is acting on behalf of the White House. Procedurally, the White House does not allow the FBI to investigate as it sees fit, the official acknowledged; the White House sets the parameters.

Committee member Sen. Dianne Feinstein sent a letter Sunday to White House counsel Don McGahn and FBI Director Christopher Wray requesting a copy of the written directive the White House sent to the FBI.

"In addition," she wrote, "if the FBI requests any expansion beyond the initial directive, please provide the names of any additional witnesses or evidence."

Trump announced on Twitter late Saturday that the White House had placed no limitation on the FBI's ability to investigate the allegations against Kavanaugh.

"I want them to interview whoever they deem appropriate, at their discretion," Trump tweeted in response to an NBC News report citing multiple people familiar with the process who said the White House was limiting the scope of the reopened background investigation of Kavanaugh.

While the FBI will examine the allegations of Christine Blasey Ford and Deborah Ramirez, the bureau had not been permitted to investigate the claims of Julie Swetnick, who has accused Kavanaugh of engaging in sexual misconduct at parties while he was a student at Georgetown Preparatory School in the 1980s, those people familiar with the investigation told NBC News.

A source confirmed to NBC News that Ramirez spoke with the FBI on Sunday, and she provided investigators with a list of witnesses she says corroborate her claim.

A member of Ford’s legal team told NBC News on Sunday that neither Ford nor her lawyers have been contacted by the FBI since Trump ordered a supplemental FBI background investigation Friday.

A White House official had confirmed earlier Saturday that Swetnick's claims would not be pursued as part of the reopened background investigation into Kavanaugh. Trump described that as incorrect in a tweet late Saturday. The Wall Street Journal had also reported that Swetnick's allegations would not be investigated.

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Trump said the FBI had "free rein" in the investigation.

"They’re going to do whatever they have to do," he said. "Whatever it is they do, they’ll be doing—things that we never even thought of. And hopefully at the conclusion everything will be fine."

The New York Times reported Saturday night, after Trump’s tweet, that the White House has authorized the FBI to interview four witnesses: Judge; Leland Keyser, a high school friend of Ford’s whom she said attended the party but was not told of the assault; P.J. Smyth, another party guest; and Ramirez, the Yale accuser.

Ford said in Senate testimony Thursday that she was "100 percent" certain that Kavanaugh sexually assaulted her when they were both in high school. Ramirez alleged that he exposed himself to her when they were students at Yale. Kavanaugh has staunchly denied allegations from Ford, Ramirez and Swetnick.

Instead of investigating Swetnick's claims, the White House counsel’s office has given the FBI a list of witnesses they are permitted to interview, according to several people who discussed the parameters on the condition of anonymity. They characterized the White House instructions as a significant constraint on the FBI investigation and caution that such a limited scope, while not unusual in normal circumstances, may make it difficult to pursue additional leads in a case in which a Supreme Court nominee has been accused of sexual assault.

The limited scope seems to be at odds with what some members of the Senate judiciary seemed to expect when they agreed to give the FBI as much as a week to investigate allegations against Kavanaugh, a federal judge who grew up in the Washington DC area and attended an elite all-boys high school before going on to Yale.

President Donald Trump said on Saturday that the FBI has "free rein" in the investigation. "They’re going to do whatever they have to do," he said. "Whatever it is they do, they’ll be doing — things that we never even thought of. And hopefully at the conclusion everything will be fine."

The president also said he thinks Flake's role in delaying the vote is fine. "Actually this could be a blessing in disguise," Trump continued. "Because having the FBI go out, do a thorough investigation, whether its three days or seven days, I think it’s going to be less than a week. But having them do a thorough investigation, I actually think will be a blessing in disguise. It’ll be a good thing."

"I don't need a backup plan," Trump said, adding that he thinks Kavanaugh is "going to be fine."

Sen. Chris Coons, D-Del., said Saturday that he supports the week-long scope of the investigation. “The FBI works at the direction of the White House in investigating the background of an administration nominee like Judge Kavanaugh," he told MSNBC's Chris Hayes at Global Citizen Festival in New York. "So it’s the White House Counsel or the president who says, ‘This is the scope of the further investigation.'"

Sen. Jeff Flake, Republican of Arizona, who led an 11th hour move in the Senate committee for an FBI inquiry, said he thought the bureau would decide how to carry it out. His Democratic colleague Sen. Sheldon Whitehouse of Rhode Island said he expected the FBI probe to include "adequate staffing," support from the committee for "rapid immunity and subpoena decisions as needed, plus the ability to investigate claims of a "penchant for drunkenness and inappropriate treatment of women, particularly where specifically related to incidents under investigation."

An FBI spokeswoman declined to comment, referring questions to the White House.

A White House official did not specifically dispute limitations on the scope of the FBI's investigation but denied the White House was “micromanaging” the inquiry.

White House spokesman Raj Shah said that "the scope and duration has been set by the Senate. The White House is letting the FBI agents do what they are trained to do.”

The Senate has only said that supplemental FBI background investigation “be limited to current credible allegations against the nominee and must be completed no later than one week from today.”

McGahn, who has shepherded Kavanaugh's nomination since President Trump chose him for the high court on July 9, is taking the lead for the White House in dealing with the FBI on the investigation, those involved in the process told NBC News.

A U.S. official briefed on the matter said its not unusual for the White House to set the parameters of an FBI background check for a presidential nominee. The FBI had no choice but to agree to these terms, the sources told NBC News, because it is conducting the background investigation on behalf of the White House.

If the FBI learns of others who can corroborate what the existing witnesses are saying, it is not clear whether agents will be able to contact them under the terms laid out by the White House, the two sources briefed on the matter said.

Some areas are off limits, the sources said.

Investigators plan to meet with Mark Judge, a high school classmate and friend of Kavanaugh's whom Ford named as a witness and participant to her alleged assault.

But as of now, the FBI cannot ask the supermarket that employed Judge for records verifying when he was employed there, one of the sources was told. Ford said in congressional testimony Thursday that those records would help her narrow the time frame of the alleged incident which she recalls happening some time in the summer of 1982 in Montgomery County, Maryland.

Two sources familiar with the investigation said the FBI will also not be able to examine why Kavanaugh’s account of his drinking at Yale University differs from those of some former classmates, who have said he was known as a heavy drinker. Those details may be pertinent to investigating claims from Ramirez who described an alleged incident of sexual misconduct she said occurred while Kavanaugh was inebriated. Ramirez's lawyer said Saturday that she had been contacted by the FBI and would cooperate.

The conditions under which the FBI's reopened background check are occurring appears to differ from the one envisioned by Flake, who used his leverage as a swing vote to pressure the Trump administration to order the FBI investigation.

Flake said Friday he thought the FBI should decide the scope of the investigation.

“They’ll have to decide — the FBI you know, how far that goes,” he told reporters. “This is limited in time and scope and I think that it's appropriate when it's a lifetime appointment and allegations this serious and we ought to let people know that we're serious about it.”

An administration official familiar with the process clarified, after the publication of this story, that while investigators may not be interviewing Swetnick herself, that doesn't preclude them from asking other witness about the allegations she has made.