When a rescue plan for Fannie Mae and Freddie Mac was hastily cobbled together over a weekend, the point man on the latest threat to the world economy was a 45-year-old Treasury official with little government experience.

The official, Anthony Ryan, was thrust into the front lines of the credit crisis after Treasury Secretary Hank Paulson's top assistant, Robert Steel, unexpectedly left to become chief executive of Wachovia. Steel had been a main architect of the Bush administration's response to the mortgage crisis. So when the shares of the two mortgage giants plunged on Friday, July 11, provoking fears of a meltdown, the job fell to Ryan, who led a team of a dozen people that came up with the bailout plan.

So far, he has received acceptable marks for putting the plan together. But the surprising wave of fierce resistance the plan initially drew from Congressional Republicans highlights the difficulties Ryan and the other top Treasury officials, all from the financial industry, face. They have little or no experience, working the levers of Congress.

Ryan had previously spent his entire career in the investment industry, most recently as a partner at Grantham Mayo Van Otterloo & Co., the Boston-based asset management firm co-founded by famed value investor Jeremy Grantham.

When Paulson, the former chief executive of Goldman Sachs, first came to Washington as Treasury secretary in May 2006, he brought along Ryan as an adviser. Exactly how this happened is not clear. In an interview with Portfolio.com, Ryan says he had never met Paulson before, although they knew many individuals in common, several of whom had recommended him to Paulson. The Treasury Secretary chose Ryan to help coach him for his Senate confirmation hearings, then brought him in when he took office.

Ryan clearly has less stature than Steel, who had been vice chairman of Goldman Sachs and who has wider and higher-level contacts in the financial industry that made it easier for him to get in touch quickly with key people during a crisis.

But supporters of Ryan say his brief time in government working with Steel and Paulson has not been an impediment.

"The last two years have aged him in experience like dog years," says Eric Mindich, a former Goldman Sachs trader and chief executive of the $12 billion hedge fund Eton Park Capital Management.

Mindich knows Ryan from a private-sector subcommittee of the President's Working Group on Financial Markets, an interagency council that was created after the stock market crash of 1987.

That group had been among Ryan's main roles, along with oversight of Treasury bonds and other financing. His job did not involve crisis management, dealing with Congress, or regulation of outside entities.

The new challenge has meant more than just a change in responsibilities. The housing and credit crises have pushed Ryan and other Bush administration officials into an unexpected regulatory, big-government role that conflicts with their long-stated free-market beliefs.

One aide to a Congressional financial committee say these officials suddenly find themselves having to fill the role that Franklin Roosevelt's brain trust did in grappling with the Depression.

In a series of speeches in recent months, Ryan has sharply criticized the financial-services industry for "the erosion of market discipline." He said this was a leading cause of the subprime meltdown.