A rendering of the proposed Eisenhower Memorial. (AP Photo/Gehry Partners LLP)

Eisenhower Memorial Commission chairman Rocco Siciliano will step down as leader of the board but will remain a member, he announced in an email sent Tuesday to commission members.

Siciliano has led the commission since its authorization in 1999. After years of delays, its Frank Gehry design – to be built on a four-acre site along Independence Avenue – received preliminary approval from both the National Capital Planning Commission and the Commission of Fine Arts.

The urban park, now expected to cost $140 million, will feature stainless steel tapestries along its southern edge, with a memorial core commemorating Eisenhower as military hero and president.

Siciliano, who is 93, is a World War II veteran who served as a special assistant to Eisenhower in the White House and later served as president of the Dwight D. Eisenhower World Affairs Institute in Washington, D.C.  The commission’s founding chairman, he suggested the board elect Sen. Pat Roberts (R-KS) to succeed him.

“With his roots in Kansas and his passion for Ike, I hope he will consider succeeding me as chairman of the Eisenhower Memorial Commission,” he wrote. “We need a tough Marine like him to bring this project to conclusion.”

The project has elicited criticism for its method of selecting an architect and for Gehry’s design, which has been maligned by members of Eisenhower’s family. Although the commission hoped to complete the memorial by 2007, the current estimate is 2018.

Roberts sent an email Wednesday to his fellow commissioners saying if they elected him chairman, he will “do my best to complete the memorial to the great Kansan and great American.” Roberts also noted progress with the family.

“David Eisenhower has advised me the Eisenhower family will support the current design and they support the completion and dedication of the memorial to their grandfather,” he wrote.

Congress has contributed $46.4 million to the project, including almost $32 million for construction. In its FY16 budget request, the commission requests an additional $68.2 million for construction, and $2 million for operations. Construction funds were requested but not appropriated in this year’s budget, which provided only operational money.  The commission will fund the balance of the costs with private donations.

The commission will meet April 29.