David Moulton, who has served on Capitol Hill for more than a quarter-century, most of it working for Rep. Ed Markey (D-Mass.), is retiring from his post as staff director of the House Energy Independence and Global Warming Committee. He will be replaced by Gerry Waldron, who comes back to Congress from a law firm and who also is a grizzled Hill veteran.

[IMGCAP(1)]Comings and goings in Congress are frequent occurrences, of course. I write about this because 20- and 30-year Hill careers used to be the norm in personal and committee offices, but no longer. Far more typical now is to find staffers who put in a few years and then leave. Some younger ones go to law, business or graduate school, others leave to work in an administration, but many more to go into the lobbying business in one form or another, usually at several multiples of their Congressional salaries. They join the many former lawmakers who do exactly the same thing. It is also striking to see someone who did leave give up the high salaries of a major law firm to return to the Hill.

It is a characteristic of the most effective Members of Congress that they attract and retain (and sometimes re-attract) the best and brightest people and use them to enhance their own scope, assets and leverage inside Congress. Markey is unquestionably one of these, with a longtime great staff of impressive loyalty and longevity. So too are his Energy and Commerce colleagues Henry Waxman (D-Calif.) and John Dingell (D-Mich.), both of whom have managed to lure back highly paid lawyers and lobbyists to work for them in the majority, and if anything have expanded the breadth and depth of their already considerable influence.

All over the Hill, from legendary Senator and boss Edward Kennedy (D-Mass.) — whose legislative director, Carey Parker, was there when I came to the Hill more than 38 years ago! — to top-flight Senators such as Dick Lugar (R-Ind.), Lamar Alexander (R-Tenn.) and Pete Domenici (R-N.M.), one finds smart, loyal and committed staffers who find fulfillment working for people they believe in, and therefore are willing to ignore for decades the lure of much higher pay.

One of the reasons people such as Sens. John McCain (R-Ariz.), Hillary Rodham Clinton (D-N.Y.), Joseph Biden (D-Del.) and Chris Dodd (D-Conn.) were able to make their presidential runs is the deep, strong, veteran, loyal staffers they have attracted and kept over their Senate careers. (For Clinton, that includes people who worked for her in the White House and decided to come back when she got elected to the Senate.)

I took early notice of Barack Obama (D-Ill.) because he started his Senate service with a first-rate staff, blending veteran Congressional talent — much of it from former Senate Majority Leader Tom Daschle’s (D-S.D.) staff, which was perhaps the best I have ever seen — with terrific intellectual depth from think tanks and universities, and with talent he brought from Illinois. He organized his office in a creative way. It was clear long before his presidential run that he was going to be a force in the Senate, through his own personal qualities and his ability to create, utilize and inspire an all-star staff.

Markey and Dingell, models in this area, long have been favorites of mine, men who never lose their zeal for shaping the policies that affect the nation, and who are adroit and wily at the politics of Congress whether in the minority or the majority. For Dingell, known to all for his ferocity (it is not always a picnic to testify in front of him), the secret to his command of loyalty is that he also is a pussycat — warm and gracious to people around him. Markey and Dingell are both strong-willed and hate to lose. They also are about as different in personal style as one can imagine for Democrats sitting on the same committee and sharing many of the same political values, though not always the same views on issues.

For one who is friends with both, the past year was a rather uncomfortable one, as they ended up in a tense dynamic over energy and the environment, focused on the battle over mileage standards for cars, but playing out against the backdrop of larger issues: the relative power of the chairman of Energy and Commerce vis-a-vis the Speaker of the House, and of the jurisdiction of the committee up against a rival select committee chaired by one of its most senior members.

In the end, I believe, both men came up winners. Markey was able to engineer the most significant policy accomplishment of the first year of the 110th Congress — the first increase in those mileage standards in decades. Dingell did not prevail, but he might well have been able to stave off the standards (and stick it to both Markey and the Speaker) by blowing up the process.

But he knew that in the end that would serve no one, and instead he used the occasion to get the best compromise he could. And he let his friends in the auto industry know that the world had changed and if they did not accept this set of standards, they would end up far worse off.

Watching up close as they both struggled through this process made me understand even better why people like David Moulton would stay for 23 years, and others like Gerry Waldron (and Dennis Fitzgibbons for Dingell) would forsake the big bucks and come back.

Norman Ornstein is a resident scholar at the American Enterprise Institute.