AURORA, COLO. -- James H. Mullen has spent the past four years helping this Denver suburb of strip malls and starter housing build its economic base, maintain services in tough budget times and develop a vision of where it wants to go.

That's why Prince William County supervisors hired him to run the county's government as it is struggling to cope with a decade of rapid growth.

The similarities between the two jurisdictions are striking. Both are communities of 230,000 with relatively low-cost housing on the edge of a large metropolitan area. Aurora, Colorado's third-largest city, and Prince William, Northern Virginia's second-largest jurisdiction, are having similar trouble keeping pace with the growing need for services and coping with traffic woes.

As Aurora's deputy city manager since 1986, Mullen repaired stormy relations between the government and business community, supervised the police and fire departments and spearheaded the construction of an award-winning $23 million courthouse.

"He's the most respected person in Aurora government . . . able to take hot issues and defuse them," said Larry D. Carter, president of the Community College of Aurora.

Mullen, 47, will start his new job as Prince William County executive, or chief administrative officer, in mid-August. He replaces Robert S. Noe Jr., who resigned in December to join a developer with substantial real estate holdings in the county.

Mullen will find Prince William straining under a tight budget and wrangling over a plan for managing the county's development through the 1990s. The political structure will change radically next year, with the first countywide election for chairman of the board of supervisors.

The new executive, who will be paid $100,000 annually, also may have to grapple with shadow of the old one. In his 11 years as county executive, Noe won admiration from staff and some elected officials for refusing to tailor his recommendations to politicians' desires. But some people thought he did not pay enough attention to details and blamed him when securities transactions caused the county's investments to lose more than $1 million a few years ago.

Mullen shares Noe's backbone but has a different attitude toward the day-to-day operation of government, said officials in Aurora and Greenwood Village, Colo., where Mullen served as city adminstrator from 1982 to 1986.

He "has an amazing attention for detail and does not forget about assignments he gave you six months ago that you kind of ignored," said Mark Franzen, Aurora's director of community services.

Aurora officials said Mullen combines his grasp of specifics with a diplomatic manner to make his advice persuasive. "He's a statesman -- very dynamic, very results-oriented," said Norman Sheldon, chairman-elect of the Aurora Chamber of Commerce. "He's just the opposite of flashy: quiet, soft-spoken, yet thorough," said former Aurora mayor Dennis Champine.

A few people said that Mullen becomes impatient with people who cannot -- or will not -- see the broad context of a decision. "He has little tolerance for the pure political ploy," said one former Aurora official who asked not to be identified. "In some instances he can be quite righteous."

"When I feel uncomfortable with {a decision}, they're going to know about it," Mullen said.

Mullen entered public administration in 1976, returning to his hometown of Charleston, S.C., to work as the assistant to Mayor Joseph P. Riley, a childhood friend. Mullen said he turned to public service because "it was idealism but also practical. I had the opportunity to cause a lot of change to happen."

After setting up Charleston's downtown revitalization project, Mullen moved west, seeking rapidly growing communities, first in Wyoming, then in Colorado, where he received a master's degree in 1970.

In Aurora, much of Mullen's innovative work came in the area of community outreach. He involved civic groups in growth planning and building code enforcement, and worked to emphasize relationships between beat police officers and residents.

"He's a delight to work with . . . . He cared about our community," said Carol Singer, of the Del Mar Parkway Neighborhood Association in Aurora.

Mullen won fans in the business community by simplifying the development process. "I had projects going through every six weeks, and every time there was a new set of regulations," said developer David Moore. "He streamlined it."

Mullen is leaving Aurora at a time when he is running out of options, according to city officials. The city manager who hired him, James R. Griesemer, left last fall after alienating much of the staff and the city council, officials said. Mullen decided not to apply for the top job, a move many city officials believed was wise.

"Jim Mullen would not have been totally different {from Griesemer}," said Mayor Paul Tauer. "He would have had an uphill battle to prove himself."

Said Mullen, "They were looking for a much lower-profile person who was . . . going to be more compliant. It was not something I wanted for me."

Aurora's police and fire unions resented Mullen's constant, and generally unsuccessful, calls for improved affirmative action efforts, officials said. Minorities make up nearly 20 percent of Aurora's population, but 6 percent of the public safety departments.

Some who work closely with Mullen said he is a compassionate and interested, albeit sometimes dictatorial, boss and a loving father to his two sons, ages 21 and 7.

"If he's on the phone with his 7-year-old, he doesn't chase you out of the room. He's not ashamed to show you he talks to his family," said Dianne Truwe, director of development services.

Mullen also has a gift for easing a tense situation with a joke, often at his own expense, some employees said. Others said Mullen, who graduated from the Air Force Academy and served four years as an officer, occasionally shows his military background.

Said one Aurora official, "Jim will do better as a leader than a deputy because he needs to be in charge."