PORTLAND — Richard D’Abate, who helped transform the Maine Historical Society from an artifact-based organization to one where a key connection among constituents revolves around the Internet and unfettered access to Maine’s digital history, announced his resignation today.

D’Abate, 65, will step down from his post in May 2012, enabling the organization ample time to find a successor.

“I will have been at it for 16 years by the time we get to the spring. We’ve accomplished a lot,” D’Abate said in a phone interview. “We have a new phase that is going to take another five to 10 years to bring to fruition, and I didn’t think I had it left in me to do that. I thought we had reached a series of accomplishments, and it’s time for other people to take over and do the rest.”

As executive director, D’Abate led the historical society through a growth period. Under his leadership, the organization completed three capital campaigns, including the restoration of the Longfellow House and a $9.8 million expansion of the Brown Research Library. In his term, the operating budget has tripled and the endowment doubled.

The next phase of Maine Historical’s master plan is the creation of a new museum. D’Abate has been involved in the early planning stages of that task, and wants to hand off the bulk of the work to his successor.