The grandchildren of Dwight David Eisenhower have given their official response to the latest iteration of a proposed memorial to the nation’s 34th president. Although the family welcomed substantial changes unveiled by architect Frank Gehry this month, including the addition of heroic-scaled statuary to the memorial’s core, it remains adamantly opposed to the fundamental architectural idea: large metal tapestries depicting scenes of the nation’s heartland.

“From our perspective, many of the changes that Gehry Partners made to the design concept are positive and welcomed,” said a letter posted Wednesday on Susan Eisenhower’s blog. “The scope and scale of the metal scrims, however, remain controversial and divisive. Not only are they the most expensive element of the Gehry design, they are also the most vulnerable to urban conditions, as well as wildlife incursions and ongoing, yet unpredictable, life-cycle costs.”

The family’s statement narrows the focus of its opposition to the memorial, planned for a four-acre site south of the Mall at Maryland and Independence avenues SW. In previous statements, and in a public hearing in March, the family not only opposed the metal scrims, but also blasted Gehry’s interpretation of Eisenhower’s legacy and criticized the Eisenhower Memorial Commission, which selected Gehry and unanimously supported his design, calling for “a top down review of its staff management practices.”

Despite the family’s continued opposition to what is the most distinctive and essential element of Gehry’s design, a spokeswoman for the commission welcomed the statement as progress toward resolving the family’s concerns. By narrowing the range of its criticism, which in the past has included references to Mao, Stalin and Hitler’s death camps, the family has made it easier for the commission to respond directly to specific concerns.

“We are absolutely delighted that they are happy with the changes,” Chris Kelley Cimko said. As for the tapestries — innovative metal scrims that would probably display scenes of the landscape near Abilene, Kan., where Eisenhower grew up — Cimko said they are undergoing rigorous testing.

But a statement released by Interior Secretary Ken Salazar suggested that the family is gaining ground in persuading political leaders to delaydelaying the memorial’s approval.

“To honor the legacy of President Eisenhower, it’s important that we build a national memorial that reflects the vision of the Commission, his family, and the American people,” wrote Salazar, who as head of the department that oversees the National Park Service has considerable sway over the outcome. “Though it is important to move forward as swiftly as possible, our priority must be in getting it right. If more time is required to get it right, so be it.

Cimko said the commission doesn’t believe the tapestries will be overwhelmingly expensive, but it will know more as the procurement process continues. It is also waiting for results from independent testing agencies that are exploring how the tapestries will behave and whether they will meet longevity standards.

“We have a very rigorous testing program that is underway right now,” Cimko said. “It is [looking at] all sorts of things like environmental issues — like, can birds see them, what is the impact of a plastic bag, what’s the impact of a Kleenex? That’s a concern that we have and that we share.”

The family’s statement frames its opposition with a new emphasis on the cost and sustainability of the memorial, and puts these concerns in the context of the economic crisis that began in 2008.

Referring to a societal “shift” in thinking about memorials that “came last summer,” the statement says: “The US and global debt crisis ushered in a new era. Today, we must learn again to celebrate things that are simple, sustainable, and affordable.”

Rep. Rob Bishop (R-Utah), who chairs the House subcommittee on national parks, forests, and public lands, used the family’s statement to call for slowing the memorial’s approval process, which could include a pivotal vote by the National Capital Planning Commission this summer.

“I remain concerned that taxpayer dollars will be used to fund construction of a memorial to President and General Dwight D. Eisenhower despite the fact that his family has expressed concern and opposition to major design components,” Bishop said in a statement. “I respect the Eisenhower family’s request that the memorial reflect the concepts: simple, sustainable, and affordable. At present, it does not appear to meet those qualifications and until a consensus can be reached, . . . I support the family’s request to hold off on moving forward with the project.”

Despite the statements by Salazar and Bishop, the memorial commission attempted to reach out to the Eisenhower family with a letter released Wednesday afternoon. Chairman Rocco C. Siciliano said he was “delighted” to read the family’s statement and underscored his group’s commitment to “the maintenance and sustainability of the entire memorial.”

Moving forward, I believe we can allay your concerns about the sustainability of the tapestries,” wrote Siciliano, who served as special assistant to President Eisenhower.

In interviews, Gehry has stressed the historic role tapestry has played in heroic narratives. But they are far from a merely incidental or decorative element of his design. Without them, the memorial would be framed by ugly office buildings, including the Department of Education building, which is one of the least inspired structures facing the Mall. Developing the tapestries was a major part of Gehry’s design process, and the unveiling of sample tapestries in September was instrumental in earning preliminary approval from the U.S. Commission of Fine Arts (which, along with the National Capital Planning Commission, must sign off on the design).

Simply removing them would probably mean the wholesale scuttling of Gehry’s design. So the family’s statement sets up two possible outcomes: The Eisenhower Memorial Commission successfully responds to practical concerns, and the memorial moves forward; or opponents of the memorial succeed in forcing the removal of the tapestries, which could delay the creation of a memorial for years or decades.