With his quick, long and purposeful stride, Douglas Elmendorf could be hiking the forested trails of the Pacific Northwest or Alaska, where he spent his last two summer vacations.

But today, in tie and jacket, a soft black leather satchel swinging from his right hand, Elmendorf, the director of the Congressional Budget Office, is hurrying along a suburban sidewalk.

It is an hour before dusk on a cloudy September evening. He is making the two-block walk at the end of the commute -- Orange-Blue Line to Red Line to Ride On bus -- from his office on the outskirts of Capitol Hill to his renovated split-level home in a Bethesda subdivision.

On this particular night, Elmendorf -- tall, wispy thin, bearded, sandy-haired and still boyish-looking at 47 -- is hurrying to get to the back-to-school night at Walt Whitman High School, where his twin daughters are freshmen.

He checks his BlackBerry several times after emerging from the Metro as the Ride On jitney rattles through Bethesda, and calls home to report that he is almost there.

Notwithstanding the early trip home this evening, it is a far cry from the much more leisurely pace of his previous job at the Brookings Institution, when he could on occasion head home in broad daylight with a much lighter briefcase, or none at all.

Still, the pressure of overseeing the Congressional Budget Office in the midst of the health care debate did not keep him from a summer hiking vacation.

He and his wife, Karen Dynan, herself a scholar at Brookings but until recently a senior adviser in the Federal Reserve's division of research and statistics, took their daughters on hiking trips through three national parks in Washington state -- the rugged North Cascades, Mount Rainier and Olympic. The year before, they went to Alaska on another hiking vacation.

"We covered a lot of ground," he said of the Pacific Northwest excursion, squeezed into a two-week break during the August congressional recess.