WASHINGTON — Attorney General Alberto Gonzales’ replacement — whoever that may be — faces a potentially nasty Senate confirmation and a beleaguered Justice Department badly in need of leadership.

Gonzales’ resignation, announced Monday, cheered his critics who for months had demanded the attorney general quit over questions about his credibility.

Filling his job could lead to a new standoff between White House Republicans and the Democratic-led Congress, experts said, even as names of possible successors began to surface.

“Selecting a successor to Gonzales will be a challenge because the Senate is unlikely to confirm anyone as aggressive as Gonzales in the defense of executive power and the practice of secrecy,” said Peter Shane, professor at The Ohio State University Moritz College of Law.

But the White House is unlikely to let Congress dictate who gets the job.

Someone like former Sen. Jack Danforth, R-Mo., for example, “might be too liberal for the base,” said Hunter College political scientist Kenneth Sherrill, referring to Republican conservatives who make up President Bush’s core supporters.

A more intriguing pick, Sherrill said, would be Sen. Joe Lieberman, the hawkish Connecticut Democrat whose nomination would allow his state’s Republican governor to appoint his replacement — wresting control of the Senate from Democrats to a tie between the two parties.

For now, Solicitor General Paul Clement will head the Justice Department until a replacement is found. Among the possible successors whose names were floated Monday:

• Homeland Security Secretary Michael Chertoff, a former assistant attorney general and federal judge who commands the legal expertise that Gonzales lacked. However, Chertoff faced intense criticism and calls for his own resignation after Homeland Security’s sluggish response to Hurricane Katrina in 2005.

• Sen. Orrin Hatch, R-Utah, the top Republican on the Senate Judiciary Committee for a decade before relinquishing that standing in 2005. In April, Hatch said “it would be really tough for me to get confirmed” but that “I would serve this country in any way I could.”

• Asa Hutchinson of Arkansas, a conservative former U.S. attorney, congressman, Drug Enforcement Administration chief and border security director at the Homeland Security Department. Hutchinson, whom an aide said was on his way to Washington on Monday afternoon, could run afoul of Democrats for his role in the impeachment of former President Clinton.

• Acting Deputy Attorney General Craig Morford, a 20-year federal prosecutor. Morford sent former Rep. Jim Traficant, D-Ohio, to jail and recommended that a federal judge toss out verdicts against two defendants in the nation’s first major post-9/11 terrorism case after finding the Justice Department failed to turn over documents to defense lawyers.

—Former Solicitor General Ted Olson, a courtly conservative whose wife, Barbara, was killed in the Sept. 11 flight that crashed into the Pentagon. Olson is now a partner at law firm Gibson, Dunn & Crutcher in Washington.

—Former Deputy Attorney General George Terwilliger, who served during the administration of President George H.W. Bush and is now a partner at White & Case in Washington.

— Former Deputy Attorney General Larry Thompson, who held the post during the current President Bush’s first two years in office and is now general counsel at Pepsi Co.

— Former Deputy Attorney General James Comey, general counsel at Lockheed Martin Co. He is considered a longshot at best after defying the White House’s orders to continue a domestic spying program when he was the Justice Department’s No. 2 in 2004.

—4th U.S. Circuit Court of Appeals Judge William Wilkins, a South Carolina jurist who has defended the Bush administration’s treatment of enemy combatants and reinstated a libel lawsuit against The New York Times over opinion columns linking a former Army scientist to the 2001 anthrax killings.