WASHINGTON (Reuters) - Democratic U.S. senators expressed concern on Sunday over reports the White House was working with Republicans to narrow the scope of an FBI investigation into sexual assault allegations against Supreme Court nominee Brett Kavanaugh.

President Donald Trump bowed to pressure from moderate members of his Republican Party on Friday and ordered the probe after Christine Blasey Ford, a university professor, detailed her allegations at a Senate hearing that Kavanaugh assaulted her in 1982, when the two were in high school.

The stunning reversal capped two weeks of allegations, followed by furious denials, that roiled prospects for Trump’s nominee, a conservative federal appeals court judge once expected to easily become the second Trump nominee to win a lifetime appointment to the top U.S. court.

Kavanaugh has denied Ford’s accusation, as well as those of two other women.

Separately, the Senate Judiciary Committee made public late on Sunday a previously unreleased interview with Kavanaugh from Sept. 26, before a public hearing with Ford, in which he denied all the allegations against him and committee Democrats declined to ask questions, saying they felt the FBI should investigate the allegations.

Republicans, who are trying to retain control of the U.S. Congress in November elections, are seeking to balance their desire for another conservative justice on the court with sensitivity about how they handle sexual misconduct allegations amid the reverberations of the #MeToo movement.

It did not take long, however, for the FBI probe to become an object of partisan division.

A White House official, speaking on condition of anonymity, told Reuters the White House had defined the parameters of the probe for the FBI and that the investigation would start with interviews with only four people.

NBC News, the New York Times and the Wall Street Journal previously reported that the White House was constraining the investigation, prompting Democrats on the Senate Judiciary Committee to express concern.

Senator Dianne Feinstein, the panel’s top Democrat, wrote to White House counsel Donald McGahn and FBI Director Christopher Wray and asked that the committee be provided with a copy of the written directive the White House sent to the FBI, as well as the names of any additional witnesses or evidence if the probe is expanded.

The White House did not respond immediately to a request for comment.

LIMITING THE PROBE

The administration denied it was trying to control the probe, which the Judiciary Committee said on Friday “would be limited to current credible allegations” and wrapped up within a week.

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“We’re staying out of the way,” White House press secretary Sarah Sanders told “Fox News Sunday.”

However, the administration made clear there would be limits. “It’s not meant to be a fishing expedition,” White House adviser Kellyanne Conway said on CNN’s “State of the Union.”

Trump vowed on Saturday that the FBI could interview “whoever they deem appropriate.”

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On Sunday, he criticized Democrats for expressing concerns about the length and scope of the probe.

“For them, it will never be enough!” he wrote on Twitter.

The FBI will question Deborah Ramirez, who said Kavanaugh exposed himself to her at a party when both were students at Yale University, the White House official told Reuters.

It will also question Mark Judge, a friend of Kavanaugh who Ford said witnessed the assault, and Leland Keyser and P.J. Smyth, who she said were at the gathering.

A third accuser, Julie Swetnick, was not on the initial list of witnesses to be interviewed.

Senate Republicans compiled the list of four witnesses and Senate Republican leader Mitch McConnell shared it with the White House, the official and another source familiar with the matter told Reuters.

The New York Times, citing people familiar with the matter, reported that the White House asked the FBI to share its findings after the initial interviews and that Trump and his advisers would then decide whether the accusations should be investigated further.

Neither the FBI nor a Judiciary Committee representative would comment on details of the probe.

Senator Susan Collins, among a handful of moderates who joined Republican Senator Jeff Flake, said in an email: “I am confident that the FBI will follow up on any leads that result from the interviews.”

Flake was instrumental in forcing the investigation.

Carl Tobias, a law professor at the University of Richmond, said it would not be unlawful for the White House to restrict the investigation’s scope because the FBI is under the executive branch.

However, Tobias said FBI agents were usually allowed to act independently and it would be a “clear conflict of interest” for White House officials involved in Kavanaugh’s confirmation process to interfere with the FBI’s investigation.