Maryland's new top federal prosecutor Tuesday declared terrorism cases to be his highest priority, charting a new direction for an office that in recent years has been both celebrated and criticized for its laser focus on public corruption.

Rod J. Rosenstein, 40, described his priorities in an interview several hours after stepping into his role as U.S. attorney. He will manage a staff of 70 prosecutors handling some of the most complex cases in the state, dismantling violent gangs and unraveling white-collar schemes.

"Our number one objective is to do everything we can to prosecute and disrupt terrorists," said Rosenstein, a Republican. In what he described as a rough ordering of his priorities, Rosenstein cited terrorism, gun crime, drug organizations and finally white-collar crime and corruption.

Those priorities mark a shift from the office as it was run by former U.S. attorney Thomas M. DiBiagio, who announced in December that he would step down after three years because of family and financial considerations. DiBiagio, also a Republican, made a point of restoring the office's tradition of aggressively prosecuting public corruption.

But critics pointed to an investigation by his office that focused on then-Lt. Gov. Kathleen Kennedy Townsend (D) during her unsuccessful run for governor in 2002 and to another probe of the Baltimore City Council, whose members are Democrats. Townsend was not charged, and DiBiagio's interim successor, Allen F. Loucks, ended the Baltimore council investigation with no charges.

Although his office won convictions against former Maryland State Police superintendent Edward T. Norris and Nathan A. Chapman Jr., a onetime chairman of the state university system's Board of Regents, DiBiagio at times was at odds with superiors at the Justice Department, where his crusade against corruption did not match the department's stated priority: terrorism.

Rosenstein lives in Bethesda with his wife, Lisa Barsoomian, and two daughters, ages 3 and 5. A former associate independent counsel in the Whitewater investigation, he ascended the ranks in the Justice Department and was most recently a high-level attorney in the department's tax division.

Rosenstein said that as a candidate for U.S. attorney, he met with Alberto Gonzales, first when Gonzales was the White House counsel and later when he was attorney general. "We talked about the importance of the office, the importance of maintaining public confidence in the office, the importance of abiding by high ethical standards and following Justice Department policies and procedures," Rosenstein said.

DiBiagio was rebuked by the Justice Department last year after urging his prosecutors to obtain "three 'front-page' white collar/public corruption indictments" before Nov. 6, four days after the presidential election. After the directive was publicized, Deputy Attorney General James B. Comey told DiBiagio that he could bring no public corruption cases "without my personal approval." Comey said he was taking the step to protect the credibility of the office.

Tuesday, Rosenstein said the key to managing the political aspect of the job "is to recognize that it's not a political job."

Rosenstein said that he and DiBiagio are friends and that they had talked about Rosenstein's new job.

"Yes, he did give me some advice," Rosenstein said.

What was it?

"I'm not going to share it," he said.

Rod Rosenstein succeeds Thomas M. DiBiagio.

The new federal prosecutor for Maryland, Rod J. Rosenstein, said his office's "number one objective is to do everything we can to prosecute and disrupt terrorists." His predecessor had emphasized prosecuting public corruption in the state.