The FBI's recent string of high-profile foul-ups could have the agency heading for some rocky times with Congress, as lawmakers begin probing the bureau's failure to turn over thousands of documents to the defense in the Timothy McVeigh case.

The chairman of the Senate Intelligence Committee said the FBI has had "too many failures, too many blunders" of late, severely undermining the American people's confidence in the bureau.

"Any kind of failure at the FBI, anything that happens at the FBI that calls into question something they did or failed to do leads to a lot of mistrust with the American people," Sen. Richard Shelby, R-Ala., said after his committee met privately with FBI Director Louis Freeh on Tuesday.

On Wednesday, Sen. Richard Durbin, a Democrat from Illinois, is expected to announce a proposal calling for greater oversight and accountability of the agency. Freeh is also expected to get an earful during a House Appropriations subcommittee hearing on the FBI budget.

Though Tuesday's Intelligence Committee briefing was ostensibly about FBI agent Robert Hanssen, who was arrested in February on charges of spying for Moscow for 15 years, the meeting quickly moved to the subject of the McVeigh case and the 1963 bombing of a church in Birmingham, Ala., that killed four young, black girls. In that case, which took decades to successfully prosecute, the FBI withheld crucial evidence from the Alabama attorney general, evidence that could have resulted in more timely convictions.

Shelby called for "a broad review of the FBI, its mission, its problems and some solutions." Shelby was particularly outraged at the FBI's lapses surrounding the Sixteenth Street Baptist Church bombing.

"From what I've learned recently, the FBI had information which they never furnished first to our former attorney general, Bill Baxley, when he reopened the bombing case" in the 1970s, "and only recently furnished it to the U.S. attorney's office in Birmingham."

The information -- including hundreds of hours of tape recordings -- helped win the May 1 murder convictions of Thomas Blanton Jr., 62, a former Ku Klux Klansman, nearly 30 years after the bombing.

The three-decade withholding of information infuriated Baxley, who convicted ex-Klansman Robert Chambliss when he reopened the probe in the 1970s.

"What excuse can the FBI have for allowing Mr. Blanton to go free for 24 years with this smoking gun evidence hidden in its files?" Baxley wrote in a May 3 commentary in The New York Times.

Shelby also said that Freeh, who announced he will retire as FBI chief June 1, is responsible for the McVeigh situation, but said others in the FBI who failed to meet deadlines or follow orders in providing the documents to the defense "ought to be brought to task."

"It's something that should not have happened, and it shows, probably, a lack of diligence somewhere in the FBI," Shelby said.

Shelby also appeared wary of Freeh's contention that newly found documents "won't have any bearing on the case."

"We'll have to wait and see," Shelby said.

The foul-up has already resulted in Attorney General John Ashcroft postponing McVeigh's execution from Wednesday to June 11, and has also caused McVeigh, who had decided not to pursue further stays of his execution, to re-evaluate that position.

Meanwhile, Sen. Orrin Hatch, R-Utah, who heads the Senate's Judiciary Committee, said the committee, which oversees the FBI, is planning hearings on the McVeigh matter. "There's no question these mistakes should not have been made in a high-profile case, or any case," Hatch said.

"Every criminal defendant has the right to these types of materials and we've got to live up to our responsibilities," said Hatch, who was not in the Freeh hearing. "We must see that those rights are protected."

Sen. Dick Durbin, D-Ill., intends to propose the creation of a separate inspector general for the FBI, supplanting the Justice Department's IG there. The new IG would report to the Governmental Affairs Committee.

Durbin is on both that panel and the Judiciary Committee.

The Associated Press contributed to this report.