It all started with Ronald Reagan.

A 13-year-old in Baltimore with an interest in politics volunteers for his first campaign -- and finds a hero for life. Twenty-two years later, Ken Mehlman is White House political director, a major force behind the Republican victories of November and the man in line to run President Bush's reelection campaign in 2004.

"My job," Mehlman says, "is to look after the president's political interests."

That's a pretty broad field, and obviously Mehlman is not the only person tending that territory. But he is the one who does the actual plowing and planting. From his office in the Eisenhower Executive Office Building, Mehlman takes the Big Ideas from his boss, Bush strategist Karl Rove, and others and does the hard, detailed work of customizing them and dispersing them to far-flung candidates and contexts.

It is Mehlman's job to spot Bush-friendly candidates for slots up and down ballots across the country. It is his job to see that the Republican National Committee, the state parties and GOP candidates are all singing from the same hymnal page. If a proposed policy is going to cost votes in one state and gain them in another, Mehlman is supposed to know which states and how many votes.

He also keeps track of favors granted and favors owed, and monitors patronage -- which he prefers to describe thus: "identifying able people around the country who can work for the president."

Obviously, success or failure in this enterprise is all in the details, which makes the job a good fit for Mehlman, who is young (36), intense, focused, disciplined, single and single-minded. He does not work all the time, he notes. "Five days a week I run, cross-train or lift. It's my release." He also reads lots of books -- books about politics.

Mehlman's rise is, on one hand, yet another version of a familiar Washington story: Smart young workaholic finds his moment. Framed wider, however, it is a glimpse of a generation shift.

The bright young things inspired by John F. Kennedy are pondering their retirement accounts. The whizzes weaned on Watergate are swamped with carpools and mortgages. In today's White House and on Capitol Hill, the staff-level momentum belongs to children of Reagan's Morning in America.

"He is one of the most important presidents our country has ever had," Mehlman summed up recently, speaking not of the man for whom he works but of the man who fired his early imagination. "Ronald Reagan certainly was one of the two most important presidents of the 20th century."

The Reagan cause enticed Mehlman to leave the legal fast-track and go to work on the Hill in 1994. He had shone at Harvard Law School and was moving up quickly at the Washington firm of Akin, Gump, Strauss, Hauer & Feld when he left to join the staff of Rep. Lamar S. Smith (R-Tex.) -- a move many of his friends found baffling.

"People said, 'Are you crazy? Going to work for the House Republicans?' " Mehlman recalled. At that point, the GOP had been in the minority in the House for 40 years. A month later, with then-Rep. Newt Gingrich (Ga.) as their leader, the Republicans took control.

Mehlman learned several useful lessons in the wild and heady period after that victory -- and from Gingrich's subsequent implosion. One was that conservatives can't only be anti: anti-tax, anti-government, anti-abortion. A positive message is required. "We need to explain to voters what the world will look like after our program is in place," Mehlman said. Otherwise they just sound grouchy.

Lesson two: "You need to show some humility."

And the third lesson: "If you propose, and continue to push for, bold initiatives that are right, chances are you will succeed."

In 1996, Fort Worth insurance executive Kay Granger was elected to Congress with guidance from the Texas GOP guru, Karl Rove. Mehlman became Granger's chief of staff, and in that role he met Rove and quickly made a favorable impression. In June 1999, Mehlman joined the Bush for President campaign as field director for Iowa and the Midwest.

He moved up quickly -- so quickly that he is the presumptive pick to leave the White House sometime in the next year or so to run Bush's reelection campaign.

This is something he would rather not discuss.

"It's an honor to serve the president, and I look forward to doing whatever I can to assist him," Mehlman dodged.

In a recent interview, Rove pinned Mehlman's success to "three crucial skills. First, he's a natural leader. He can take a group of people -- and political campaigns involve a lot of people, and it's easy for some to wander off the reservation -- he's good at keeping a vision in front of them.

"Second, he is well-organized," Rove continued. "He knows how to take a complex task and break it down into steps. And he has great political instincts."

Add discipline to that list. Reporters have been known to roll their eyes at Mehlman's steely, rapid-fire delivery of the official White House message -- never a hint of cynicism or a maverick note. This is no crusty pol with a lot of war stories he likes to tell. He says things such as "we're not focused on 2004."

"A cold, smart fellow," one Florida political journalist said after his first experience of listening to Mehlman. "Underline cold."

But Mary Matalin, a veteran political adviser to both Presidents Bush, says Mehlman has a light touch with colleagues and a quick sense of humor. "Everyone loves him," she said.

Mehlman was caught off-message only once last year. The slide-show text of a secret briefing by Mehlman somehow fell into enemy hands. Democrats gloated over Mehlman's dire predictions that a half-dozen Republican Senate candidates were in serious trouble in their races. He said sheepishly that he had been using outdated material and insisted that his party would do well on Election Day -- which, it turned out, was both on-message and correct.

Which suggests that it may be worth paying attention to his on-message statements even now. Mehlman says the Reagan lesson is that "good policy makes good politics," and that voters reward a politician who has "a strong and continuing message" that matches his actions.

"Our job is to have the people in place in Congress and in the administration to make those policies," he said. With both houses of Congress in Republican hands, Bush has the people he wanted.

The job now, Mehlman said, is to deliver results. "That's how political success is achieved."

Ken Mehlman, White House political director, customizes Big Ideas for smaller contexts.