In a 10th-floor office a few blocks from the White House is a self-described government in waiting, ready to push detailed proposals for the economy, Iraq and scores of other issues if Barack Obama becomes president.

The Center for American Progress, formed five years ago by top aides to former President Clinton, could become Washington's most influential think tank overnight. It is about to publish a 50-chapter book on how to run a Democratic administration, and many Obama aides have perused its 26-page document describing what the last five presidents did on each day of his transition.

Of course, the group's efforts will go for naught if Obama loses to Republican John McCain. But if Obama wins, one of the first people he will turn to is John Podesta, the founder and president of the center and the man Obama tapped this fall to head his transition planning.

Podesta, Clinton's former White House chief of staff, helped create the Center for American Progress in 2003 to counteract conservative think tanks. Many other former Clinton aides and Democratic activists joined him there, and some will be eager to fill top slots in an Obama administration.

More than a year ago, the center commissioned about 60 people to write articles for its forthcoming book, "Changing America: A Progressive Blueprint." Obama can ignore its department-by-department suggestions, certainly. But with Podesta heading both the think tank and Obama's transition, that seems unlikely.

McCain also has a transition team, headed by former Navy Secretary John Lehman. Political insiders say it's essential, not presumptuous, for presidential nominees to launch transition plans before the campaign ends, provided they do so discreetly.

Podesta modeled the Center for American Progress on the conservative Heritage Foundation, which gained fame by offering ideas, strategies and personnel to Ronald Reagan when he won the presidency in 1980. Heritage published the first such hefty think tank blueprint that year, outlining conservative ideas.

Wealthy liberals including George Soros provided the Center for American Progress an initial budget of about $10 million and 75 staffers. Now it has about 150 staffers and spends more than $25 million a year.

Its reputation is solid among government insiders, and one of its blogs, Think Progress, gets heavy traffic. But the center could instantly vault to greater visibility and importance if Obama is elected and perceived to be turning to it for political and intellectual support.

CAP can become a near equal to the larger and wealthier Heritage Foundation "if they play their cards right and become Obama's favorite think tank," said Heritage vice president Michael Franc.

CAP isn't shy about its ambitions. Its roles include being a Democratic "government in waiting," said spokeswoman Jennifer Palmieri, another former Clinton White House official.

But the center will speak out when it disagrees with an Obama administration policy or action, she said. "There will be times we will be an irritant," Palmieri said.

The center offers ideas on a range of domestic and foreign issues through its Web site, events, publications and media outreach. Many proposals are similar to Obama's, but not always identical.

CAP's health care blueprint, for instance, calls for giving some people refundable tax credits to help them pay medical insurance premiums. Obama has a similar plan for the needy. CAP would require Americans to acquire health insurance or pay a fee to help fund the health care they would use if sick or injured. Obama, however, would not require adults to obtain coverage; he says his incentives would prompt a great majority to do so.

The "Progressive Blueprint," scheduled for release by Basic Books a few days after the election if Obama wins, will offer detailed proposals to the new administration on dozens of topics. Many of the writers were prominent in the Clinton administration, according to a summary provided to The Associated Press.

They include former National Security Adviser Sandy Berger; former economic advisers Gene Sperling and Laura Tyson; former Housing Secretary Henry Cisneros; and former Federal Emergency Management Director James Lee Witt. Former Clinton White House aides P.J. Crowley and Steve Richetti wrote the chapter on homeland preparedness. Former White House staff secretary Todd Stern wrote the chapter on the National Energy Council. Clinton's impeachment trial lawyer, Gregory Craig, wrote the State Department chapter.

Podesta, who declined to be interviewed, wrote the book's preface and its White House overview. The book's co-editors are consumer activist Mark Green of New York and CAP senior fellow Michele Jolin.

Podesta, 59, is a low-key, intense lawyer who has devoted most of his career to government work and teaching law.

His recently published book, "The Power of Progress," includes a hypothetical inaugural address for the next president. When Obama named Podesta his transition chief, the McCain campaign said Obama was so overconfident he'd already had an inaugural address drafted. Palmieri said Podesta never intended Obama to deliver the speech but wrote it as a way to express his own ideas for a new administration.

Podesta's speech says the nation must make "three extraordinary transformations" -- in energy production and consumption; a reinvigorated economy; and a new national security structure including more interaction with other nations.

If McCain wins, Podesta's speech will quickly lose relevance. And Basic Books would certainly lose interest in the "Progressive Blueprint," Palmieri said, so the Center for American Progress would probably self-publish.