The sudden resignation of Martha’s Vineyard Museum executive director Matthew Stackpole has shaken the 85-year-old county historical society as it plots a move from its home base in Edgartown to West Tisbury.

The museum announced abruptly on Wednesday that Mr. Stackpole has resigned after eight years on the job. Mr. Stackpole, who is a well-known presence in the Island community and has held a number of leadership positions here, will leave his post at the end of the year. “I have decided it is time for me to leave so the organization can seek the leadership and energy this Island’s history, our collection and board and staff deserve,” Mr. Stackpole said in a prepared statement put out by the museum on Wednesday afternoon.

Mr. Stackpole could not be reached for comment before press time yesterday.

The announcement is a change from just six weeks ago, when the museum announced that Mr. Stackpole would retain his title as executive director but share leadership responsibilities with Keith Gorman, the former director of archives and librarian at the museum. Mr. Gorman will now take over as executive director on Jan. 1, 2008.

The shakeup comes at a pivotal time for the museum, which is struggling to get an ambitious $26 million capital campaign off the ground. Museum leaders plan to relocate the former historical society from its campus off School street in the heart of the Edgartown historic village to a 10-acre property off State Road in West Tisbury. Purchased five years ago for $1 million, the property is located between the Polly Hill Arboretum and the Martha’s Vineyard Agricultural Society hall. Current plans envision a large new complex, including a reconstructed antique barn on the site, to house and display the museum’s extensive and valuable collection of historic artifacts.

Two years in the making, the $26 million capital campaign has to date seen only a soft launch, and no announcements have been made about how much money has been collected.

Board leaders said yesterday that they regret Mr. Stackpole’s decision to resign.

“We’re very sad to receive Matthew’s resignation — that is the absolute, honest truth,” said museum board chairman Chris Morse. “We all love Matthew and there is no more enthusiastic and honest supporter of the museum than Matthew,” he added.

“He’s a great guy and he’s been the voice for this museum on this Island for years and has done a lot of great things for the museum,” said board president Warren Hollinshead. He continued: “The attitude he has shown in his resignation is a positive one, and he has offered to continue to help us as a consultant. I expect that we will do just that — but as he said, he felt he had done what he could do for the museum, for our move to West Tisbury, and he felt it was time for new management to be brought in.”

The museum’s capital building campaign comes on the heels of the Martha’s Vineyard Hospital’s $42 million building campaign, recently completed and by far the largest fund-raising project in the history of the Vineyard. There is private concern among some museum board members and other philanthropic leaders on the Island about whether the Vineyard, even with its many generous and deep-pocketed donors, can support another capital campaign of such magnitude. Recently another large capital campaign on the Vineyard — the $14 million YMCA project — announced a delay in the start of construction because not enough money has been raised.

Mr. Morse and Mr. Hollinshead both acknowledged yesterday that the timing of the museum campaign has been difficult, but they remained confident that the campaign can be a success.

“I am not worried — certainly it is going to be a challenge but I do feel the capacity for this kind of project exists on the Vineyard,” Mr. Morse said. He also said:

“We are still in the silent phase — we don’t want to go public with this until we’re sure we’re prepared. To a degree we wanted to wait for the hospital campaign to come to a conclusion and we are very familiar with the YMCA campaign — this has been a bit of a timing issue.”

Mr. Morse would not comment on the specifics of the campaign and declined to say how much money has been raised to date. He did confirm that $75,000 has been raised to dismantle an antique barn in the town of Shirley and bring it to the Vineyard. The museum is working with Rick Anderson, a West Tisbury contractor who specializes in dismantling and rebuilding antique barns and houses on the Island. Mr. Anderson was responsible for the agricultural society barn in West Tisbury. “That part of the project is very existing and has been very well received,” Mr. Morse said.

But he said the campaign as yet has no timetable.

“We are still working through plans that we feel are appropriate and community-based,” he said.

Museum leaders have said that the move to West Tisbury is also dependent on the future sale of most of their Edgartown campus, excluding the Cooke House, which dates to 1765 and will continue to be used as a public museum.

This summer the museum named David McCullough, the Pulitizer-prize winning and nationally renowned historian who lives in West Tisbury, as honorary chairman of the capital campaign.

Mr. Morse said yesterday that he could not confirm for certain that Mr. McCullough will stay on, given the news of Mr. Stackpole’s resignation. “We hope so — we have an e-mail out to speak to him. He has been a wonderful supporter,” Mr. Morse said.

Mr. Hollinshead also admitted the campaign had gotten off to a slow start, but he too expressed continued confidence.

“It is taking us longer than we had planned, but I think things are happening. It’s not like raising money for a college or university where you have a loyal alumnae group, and there are a lot of other good causes out there on the Vineyard right now,” he said, adding:

“But there was a great deal of excitement this summer about taking the first steps and about doing something with a barn on the West Tisbury site.”

Mr. Hollingshead said he expects Mr. Gorman will do an excellent job. “We have full confidence in Keith Gorman as our new executive director, who has a professional background as a historian and archivist,” he said.

Mr. Gorman joined the museum in 2004 after working at the Smithsonian’s archives in Washington, D.C. He currently spends one week a month out of state with his family and three weeks a month on the Island.

Mr. Morse said he did not know whether that arrangement would continue once Mr. Gorman assumes full responsibility as executive director.

The museum, which sponsors a wide array of educational programs and exhibits that draw on its rich repository of Island history, depends heavily on fundraising to pay for operating expenses and balance its books each year. The museum does not publicly release its financial statements, outside of a summary statement in its annual report. In the 2006 annual report the museum reported total operating income of $833,000, including more than $470,000 from gifts and contributions. Total expenses were reported at $816,000. No capital campaign contributions were recorded in 2006; the museum reported temporarily restricted funds of $716,000 from previous years.