The recent resignation of the president of one of the nation’s most successful conservative political groups, the Club for Growth, was part of a broader power struggle over the organization’s governance and its stance on policy issues, according to sources inside and outside the group.

The Club for Growth announced last month that its president, Stephen Moore, was leaving to start a new organization with a similar outlook, the Free Enterprise Fund. The club’s statements about the change, including a letter from Mr. Moore, portrayed the transition as an amicable “passing [of] the torch” from Mr. Moore to the new president, Patrick Toomey.

However, sources familiar with the inner workings of the group said Mr. Moore’s departure followed heated disagreements with the club’s four-person board of directors.

The rift over governance of the group also led a vaunted economist, Arthur Laffer, to quit the club’s board in recent weeks. Other founders of the club and members of its economic advisory pan el have also taken sides in the dispute.

In his January 7 letter to the club’s members, Mr. Moore said he was “happy to announce” the appointment of Mr. Toomey, a former congressman who nearly defeated Senator Specter of Pennsylvania in the GOP primary last year. Mr. Moore said he planned to focus his efforts on the Free Enterprise Fund, “an exciting new venture which will complement the club’s work.” He said the organization would advocate for simplification of the tax code, reforms to the legal system, and private Social Security accounts.

Mr. Moore acknowledged yesterday that his departure from the club was more akin to a divorce than a natural parting of the ways.

“I don’t really want to talk about it, quite frankly,” the 44-year-old activist told The New York Sun. “At some point, we may go public with what the real story is. We’re trying to do it with as little acrimony as possible.”

Mr. Moore said that he and the club’s leadership essentially agreed to break the organization in two, with Mr. Moore taking control of the policy arm and the board retaining control of the entity that raises funds for political races.

“I took the 501(c)(4). They took the 527,” said Mr. Moore, referring to the provisions of the tax code under which the nonprofit groups are organized.

The Club for Growth was founded in 1999 by prominent conservatives eager to organize support for candidates who believe in low taxes and small government. Over the past five years, under Mr. Moore’s leadership, the club gained renown for its brash tactics. It unapologetically targeted moderate GOP candidates, such as Senator Specter of Pennsylvania, labeling them as “Republicans in name only.”

The group also proudly embraced its status under section 527 of the tax code, an arrangement that allows unlimited donations from individuals at a time when the White House and the Republican establishment were decrying such activity as a violation of campaign finance laws.

In an interview yesterday, Mr. Laffer said board members had repeatedly differed with Mr. Moore about the direction and management of the club.

“I patched things up a couple of times before, but I couldn’t this time,” said Mr. Laffer, best known for describing the Laffer Curve, which predicts that tax revenues will increase as taxes are cut.

Mr. Laffer said he resigned because he was tired of mediating the disagreements. “If I wanted to be on a board with these kinds of problems, I would at least get paid,” he said. Mr. Laffer said Mr. Moore declined to take a financial settlement that included a two-year agreement not to compete with the club.

Club for Growth’s executive director, David Keating, declined to describe in detail what led to the departures of Messrs. Laffer and Moore.

“Everyone’s speaking off the same sheet here,” Mr. Keating said in telephone interview. He pointed a reporter to written statements on the organization’s Web site. “Those statements pretty much say it all,” he said.

An aide to the club’s chairman, Richard Gilder, said he was traveling overseas. Thomas Rhodes, a board member who is president of National Review magazine and a former partner at Goldman Sachs, did not return a call seeking comment. Another member of the board, Jackson Stephens Jr. of Little Rock, Ark., referred a reporter’s inquiry to Mr. Keating.

Mr. Toomey, who has assumed his new duties at the club, did not return a call seeking comment for this story.

Before joining the club, Mr. Moore worked as director of fiscal policy studies at the libertarian Cato Institute and as a budget analyst for the Heritage Foundation. He also served as an economist on Capitol Hill for a former Texas congressman, Rep. Dick Armey. In recent years, as the public face of the club, Mr. Moore was a frequent guest on television talk shows and news broadcasts.

The club now boasts nearly 30,000 members and raised $22 million last year for pro-growth candidates.

Two club insiders, who spoke on the condition that they not be named, said that as the group has grown, rifts have developed over how much influence its founders should have on setting policy and selecting candidates to support.

“Some of us believe there should be votes on everything,” said one club member.

Another person closely involved with the club said Mr. Moore was not given proper credit for his work building the organization. “I was very unhappy with the way they treated Steve Moore,” the insider said. “I felt Moore built the thing into the power it became. I felt he was not treated well at all.”

Sources said a founder of the Club for Growth, Lawrence Kudlow, was among those who objected to Mr. Moore’s ouster.

In an interview Monday, Mr. Kudlow, who is a commentator for CNBC, stressed his support for the longtime conservative organizer.

“I am a strong supporter of Steve Moore. I think he’s done a great job for the cause of economic freedom and market economies,” Mr. Kudlow said. He said he plans to back Mr. Moore’s new project but has not decided what role he will play with the club in the future.

“I haven’t figured out yet what I’m going to do,” he said.

One club member said there was also a disagreement over whether to back newly-elected Senator DeMint of South Carolina in a GOP primary fight last year with a former governor of the state, David Beasley. The group ultimately threw its weight and its money behind Mr. DeMint.

The chairman of the American Conservative Union, David Keene, said Mr. Moore’s departure was a blow to the club.

“From the standpoint of the role he filled, it was unfortunate,” Mr. Keene said. “Whether or not you agree with everything he did, he was what I think brought them from an organization that was just around to an organization that played a pivotal role.”

Mr. Keene said the tensions between the board and Mr. Moore were not surprising, given the personality needed to build an effective enterprise from scratch. “Historically, most successful political organizations are a reflection of the energy and imagination of a real political entrepreneur,” Mr. Keene said. He noted that other right-leaning political groups, such as the National Conservative Political Action Committee, have imploded after their guiding lights stepped down.

“When Terry Dolan left, NCPAC vanished,” Mr. Keene said. “The biggest difficulty these organizations have is trying to institutionalize.”

Some club members attributed Mr. Moore’s departure, in part, to disagreements over the details of plans to reform the Social Security program.

Mr. Moore said he had policy disagreements with the club’s board, but they were not the primary reason for his resignation.

At the moment, there is no sign the club plans to abandon or curtail its efforts at issue advocacy, and it recently started a new Web site devoted to Social Security reform.

For his part, Mr. Moore does not appear to be giving up political fund-raising. He recently signed on as executive director of the Monday Meeting, a Manhattan-based political discussion group that is planning to dramatically increase its efforts to raise funds for conservative candidates.

Despite the public pronouncements about the club and the Free Enterprise Fund complementing each other, Mr. Moore acknowledged that some rivalry between the groups is likely. Given that everyone involved is a dyed-in-the-wool devotee of free markets, that may not be such a bad result.

“Competition is a good thing,” Mr. Moore said.