By Mark Willen, Senior Political Editor June 22, 2009 Question: What do Kathleen Merrigan, Joshua Sharfstein, Demetrios Marantis and Jordan Barab have in common? Answer: They all served as key aides to Democrats on Capitol Hill before taking high level positions in the Obama administration. And that's one reason why this president may have more success with Congress than some of his predecessors even though he's tackling the most ambitious legislative agenda since the New Deal.He's the first president in a long time to come from the Hill, but to a larger degree than many previous presidents, he is calling upon legislative expertise rather than relying solely on business leaders and those who helped get him elected.Merrigan, a former Senate Agriculture Committee staffer, now is assistant secretary of Agriculture, Sharfstein, a former staffer to Rep. Henry Waxman, the chairman of the committee with jurisdiction over health, is the principal deputy commissioner of the Food and Drug Administration. Marantis has gone from being chief trade counsel for the Senate Finance Committee to deputy U.S. Trade Representative. And Barab, who worked for House Education and Labor Committee Chairman George Miller, is a deputy assistant secretary of Labor and acting head of OSHA. Sponsored Content Every president draws on members of Congress and their staffs in stocking a new administration, but perhaps no one has gone to the lengths Obama has. Four of his Cabinet secretaries, his CIA chief and his chief of staff are all ex-members, as are he and his vice president. And about one-third of his administration appointees so far have Capitol Hill experience, according to a National Journal survey. Advertisement The unprecedented ties have already helped ease the way for Obama initiatives, allowing him to avoid the mistakes of outsiders like Bill Clinton and Jimmy Carter, who ruffled plenty of feathers by ignoring congressional etiquette. Obama has still made a few silly mistakes -- like announcing a trade agenda without telling Senate Finance Chairman Max Baucus, but they've been far fewer than his predecessors. This doesn't mean Obama will get his way in all or even most cases. On big policy initiatives, it will take a lot more than contacts to win approval. But keeping everybody informed,soliciting their input and making them feel involved can only help. There's also a risk...and pulling in senior Hill staffers can be a double-edged sword. They often come with their own agendas, a result of eight years under President bush when Republicans were able to block many Democratic initiatives. To the extent, their goals coincide with Obama's, it's all well and good. But when they diverge, it's a recipe for conflict.