More than four years ago, the city of Miami eagerly embraced an ambitious scheme for the park portion of the mega-million-dollar Museum Park project on the bay in downtown Miami.

Unanimously approved by the City Commission, the plan for a $68 million, 20-acre green space was supposed to turn most of near-derelict Bicentennial Park into Miami’s version of Chicago’s celebrated Millennium Park. The vision: lure thousands of visitors with lush public gardens, a dramatic entrance on Biscayne Boulevard with rows of royal palms growing out of a shallow pool, a great lawn, glass pavilions and a sculpted mound to provide visitors sweeping vistas of water and greenery.

Well, scratch all that. At least for the foreseeable future.

Facing a daunting fiscal crunch, city administrators have drastically scaled back the long-delayed park plan to a roughly $10 million basic blueprint. City officials have put aside most of the park’s distinctive features until an undetermined future date to focus on building two key if also simplified elements: a new baywalk, and a promenade from Biscayne Boulevard to Biscayne Bay that will provide pedestrian access to the art and science museums now rising on Bicentennial’s north end.

There will still be a park with trees, sod and pathways between the promenade and the deepwater boat slip that marks the project’s southern boundary, city leaders pledge.

It just won’t be anything like the elaborate plan that the city paid the New York firm of Cooper Robertson & Partners, famed planners of Battery Park City on Manhattan’s lower tip, $4.2 million to design.

“It will be trees and open space,’’ said city Commissioner Marc Sarnoff, chairman of the Omni Community Redevelopment Agency, which is funding the bulk of the park project. “You will be able to walk around, take a nap under a tree, play soccer. But it will not have that Millennium identity.’’

‘Still the vision’

Sarnoff and city administrators, who are now weighing five bids from contractors for the baywalk and promenade, say the reduced scope of work will include some needed environmental remediation to cover contaminated soil as well as basic infrastructure so that the Cooper Robertson plan can some day be realized.

“That’s still the vision our commission has embraced, although it was a few years ago,’’ said assistant city manager Alice Bravo. “We’re putting in the bones. We’re going to have an aesthetically pleasing park that will be in harmony with the museums and over time can be enhanced further.’’

The city had previously, and quietly, discarded some costlier elements of the Cooper Robertson plan, including a planned underground parking garage and a restaurant, reducing the estimated cost to around $45 million.

But the decision to scale back the park plan much further comes as the $220 million art museum building reaches the halfway point in construction, on schedule for a fall 2013 opening. The new Miami Science Museum, due for completion by the end of 2014, broke ground in February.

The museums, which occupy about eight acres just south of the ramp to the MacArthur Causeway, have their own extensive landscaping plan by Miami’s ArquitectonicaGeo. So will a broad plaza between the two museums that is being designed by James Corner Field Operations, the New York firm that collaborated on the wildly popular High Line, the abandoned elevated rail line in lower Manhattan that was converted into a linear park.