Robert Raben was quoted by the Wall Street Journal for his expertise as a former Justice Department official.

Robert Raben, a senior department official in the Democratic administration of former President Bill Clinton, said Mr. Sessions’ comments criticizing Mr. Grassley’s bill, as the senator was seeking to build support, were surprisingly harsh.

“This goes well beyond what is necessary to modify or slow down legislation,” Mr. Raben said. “There were 75 other ways to do this short of going to Mach 10.”

Attorney General Jeff Sessions Is Battling His Own GOP on Multiple Fronts

Sessions calls senator’s bill a ‘grave error.’ In response, senator says he is ‘really irritated.’

By Aruna Viswanatha and Del Quentin Wilber

Attorney General Jeff Sessions is fighting on multiple fronts, embroiled in disputes with Republican lawmakers on at least three issues while his Justice Department remains at odds with the White House on others.

On Thursday, Sen. Chuck Grassley (R., Iowa), who runs the Senate Judiciary Committee with oversight of the Justice Department, launched into a strong critique of Mr. Sessions in response to a letter from the attorney general that described legislation championed by the senator as a “grave error.”

“He is now attorney general and is charged with executing the laws that Congress passes, not interfering with the legislative process,” Mr. Grassley said. “I’m really irritated that he would send that letter,” said Mr. Grassley, his voice rising as he departed from prepared remarks.

That dispute erupted as Mr. Sessions was fighting with other Republican senators on issues ranging from immigration to marijuana. Mr. Sessions served in the Senate as a Republican representing Alabama for two decades before joining President Donald Trump’s administration.

Last month, Mr. Sessions’ Justice Department criticized House Republicans over the release of a memo about alleged abuses in the process for obtaining surveillance warrants, saying their plan to release the memo without his department’s review was “extraordinarily reckless.”

Sens. Grassley and Lindsey Graham (R., S.C.) also questioned whether that surveillance had been handled properly.

Earlier this week, Christopher Wray, director of the Federal Bureau of Investigation, provided a timeline of events surrounding a background review of a former senior White House official who resigned following domestic-abuse allegations. Mr. Wray’s timeline contradicted a version of events provided by the West Wing, highlighting tensions between the two.

A spokeswoman for Mr. Sessions declined to comment.

Robert Raben, a senior department official in the Democratic administration of former President Bill Clinton, said Mr. Sessions’ comments criticizing Mr. Grassley’s bill, as the senator was seeking to build support, were surprisingly harsh.

“This goes well beyond what is necessary to modify or slow down legislation,” Mr. Raben said. “There were 75 other ways to do this short of going to Mach 10.”

Separately, on Thursday morning, Mr. Sessions used a speech before county sheriffs to criticize another bipartisan legislative effort, an immigration plan introduced by Sens. Mike Rounds (R., S.D.) and Angus King (I., Maine), which failed to get the necessary 60 Senate votes late in the day.

“I’ve seen these proposals before, and I know what this means,” said Mr. Sessions, echoing the president’s position. “This is open borders and mass amnesty and the opposite of what the American people support.”

Some experts said these fights could cost Mr. Sessions allies in the Senate at a time when he has few friends in the administration. Mr. Trump, a Republican, has been displeased with Mr. Sessions since the attorney general recused himself last March from overseeing the federal investigation into Russia’s alleged meddling in the 2016 presidential election.

Earlier this week, in another speech, Mr. Sessions complained about Sen. Cory Gardner (R, Colo.) who has held up Justice Department nominees to express his displeasure over Mr. Sessions’ stance on marijuana prosecution.

Last month Mr. Sessions rescinded policies advanced by Mr. Trump’s Democratic predecessor that took a largely hands-off approach to enforcing federal marijuana laws in states, including Colorado, that have legalized the drug for medical or recreational purposes.

With “one senator’s concerns over unrelated issues, like reversing federal law against marijuana, we can’t even get a vote,” Mr. Sessions said. “We need our nominees confirmed—safety and security are important,” he said.

On Thursday, Sen. Gardner said he had lifted his hold on some Justice Department nominees, citing “positive conversations” with Deputy Attorney General Rod Rosenstein and others. He said he would continue to block other nominees while discussions continued.

The fight over sentencing legislation—the issue that sparked Mr. Grassley’s comments on Thursday—is one of the most personal. Mr. Grassley has spent years pushing changes to the criminal-justice system, producing legislation to cut mandatory minimum sentences for nonviolent offenders and establish programs to help reduce recidivism.

Mr. Sessions, for his part, has spent his tenure at the Justice Department confronting rising overdose deaths and a violent crime rate that has trended upward in some cities, focusing his efforts on providing law enforcement more tools. Mr. Grassley’s legislation could have “potentially dire consequences” in countering those efforts, Mr. Sessions wrote in his letter to Congress.

This dispute also reflects a growing division among conservatives on criminal-justice issues. Some have become more open to rethinking sentencing laws in the wake of the opioid epidemic, while others have adhered to a longstanding tough-on-crime approach that includes lengthy prison terms.

In his opening remarks on his bill Thursday, Mr. Grassley read from prepared remarks, then stopped, saying his staff hadn’t adequately expressed his displeasure with Mr. Sessions.

“I consider General Sessions a friend,” Mr. Grassley said. He went on to list a series of events that he said showed his willingness to help Mr. Sessions, including the controversial nature of Mr. Sessions’ own nomination and that of several other top department officials, as well as Mr. Trump’s threat to fire Mr. Sessions last year.

“I went to his defense,” Mr. Grassley said, referring to his promise not to consider other attorney general nominees if Mr. Sessions were dismissed.

The committee approved the sentencing legislation on a 16-5 vote, with support from Democrats, including Sen. Richard Durbin of Illinois.

“If the test of whether we pass this bill out of committee is whether Attorney General Jeff Sessions will support it, nothing is going to pass,” Mr. Durbin said.

Appeared in the February 16, 2018, print edition as ‘Attorney General Faces Multiple Battles.’