Sen. Jeff Merkley (D., Ore.) blasted the FBI investigation into Supreme Court nominee Brett Kavanaugh as a "horrific cover-up" on Thursday, calling it an embarrassment for the bureau's reputation.

Senate Democrats clamored for weeks for an expanded background check into Kavanaugh following public allegations of sexual misconduct against him, which the judge has denied. The White House acquiesced after pressure from key Senate Republicans last week, and the investigation appeared to have revealed no corroborating evidence for any of the claims made against Kavanaugh.

"It's a complete cover-up," Merkley said on CNN. "Just as it was explained that Deborah Ramirez's team, they provided 20 people who should be interviewed because they had corroborating information, and none of them apparently were talked to. We have Dr. Ford, who provided eight names and none of them were talked to. This was a cherry-picking of a few individuals to pretend to do an investigation. This is a complete embarrassment on the reputation of the FBI. If they did this at the direction of the president, then it's a massive abuse of fairness and justice towards these women who came forward to share their experiences."

Merkley called it a "horrific cover-up" and blasted the FBI for not speaking to certain people who asked to be heard.

Senate Minority Leader Chuck Schumer (D., N.Y.) said his fears that the FBI would be limited in their scope had been "realized" in a press conference.

Other Democrats have said it was "incomplete," with Sen. Dianne Feinstein (D., Calif.) wondering Thursday if it was limited by the White House, adding, "I don't know." Sen. Tim Kaine (D., Va.) called it a "sham" in remarks to reporters, and Sen. Kamala Harris (D., Calif.) tweeted it was "entirely incomplete and insufficient."

The FBI report on Judge Kavanaugh is entirely incomplete and insufficient. There are dozens of witnesses who have not been interviewed. This is for a lifetime appointment. The American people deserve to have all the facts. — Kamala Harris (@SenKamalaHarris) October 4, 2018

Wolf Blitzer asked Merkley to explain why Republican Sens. Susan Collins (R., Maine) and Jeff Flake (R., Ariz.), who have been on the fence about Kavanaugh's confirmation, were more upbeat about being briefed on the investigation. Collins called the investigation "very thorough," while Flake said it didn't offer corroborating evidence for the claims made against him.

Merkley retorted Democrats were briefed by Democratic staff and suggested they were the only ones who gave an "honest" assessment of the investigation.

"I assume that they were briefed by Republican staff," Merkley said. "So, that is not an honest examination of the issues."

He said he would try to convince his GOP colleagues that the investigation couldn't be "construed as comprehensive."

"This is not a comprehensive or fair investigation," he said.