WASHINGTON — When President Bush shakes 1,000 hands, Blake Gottesman is ready with the Purell. When Bush is in his daily intelligence briefing in the trailer on his ranch, Gottesman is on site to dog-sit Barney, the president's Scottish terrier. When a member of the White House senior staff wants a word with the boss, Gottesman is there to recommend yes or no.

"People will say, 'Is this a good time to raise something?' " said Joe Hagin, the White House deputy chief of staff. "And Blake will say, 'Well, he's reviewing a speech right now,' or 'He's got a couple of members of Congress up in the stateroom on the plane, so it would be better to wait half an hour.' "

Part Sherpa, part butler, part air-traffic controller, Gottesman, 25, is the president's personal aide. It is a job steeped in the minutiae of carrying Bush's Altoids, Sharpie markers and hand sanitizer, and in the delicacy of handling the check on the rare occasions when the president dines out. Gottesman also keeps track of the paper flow to the president, logs all his meetings and phone calls, and questions senior aides about grammar and phrasing in Bush's speech texts.

"He'll say, 'You probably ought to take a look at this word,' " Hagin said.

Gottesman, who dated the president's daughter Jenna in high school, provides a glimpse into the prosaic behind-the-Oval-Office-doors daily life of the modern White House and the needs and habits of Bush. Few people spend more waking hours with the president, and almost no one is better, senior aides say, at anticipating his next move.

Hagin compares Gottesman to Radar O'Reilly, the clerk in the movie and television series "MASH," who knew what the colonel was going to say before he said it.

"He anticipates and thinks three or four steps ahead of everyone else," said Hagin, who was the personal aide to George H.W. Bush when he was vice president.

Gottesman, who makes about $70,000 a year, declined to be interviewed for this article, saying that cooperation would paint him as a publicity hound. Senior staff members describe him as precocious, self-effacing and savvy enough to know that calling attention to himself would not sit well with the president, who has a low tolerance for self-promotion by members of his staff.

"Blake is extremely, extremely aware that this is all about President Bush and not about him," said Gottesman's friend Reed Dickens, a former aide in the White House press office and in Bush's 2004 campaign. "His dominant characteristic is how humble he is."

Senior staff members say that Gottesman, the son of an Austin real estate developer, is exceptionally close to Bush, who first got to know him as Jenna's boyfriend when Bush was an owner of the Texas Rangers. Last summer, in a Bush family interview with People magazine, Bush said that his twin daughters' taste in men was "excellent" and that they liked people who were "polite" and "not afraid of the old man, which is good."