A leading preservation group says it will submit an application to the city of Miami to have The Miami Herald’s bay-front building designated a protected landmark, setting the stage for intense debate over the structure’s architectural and historic value as well as the effect that saving it would have on a blueprint for a $3.8 billion casino resort on the site.

Some experts in preservation say Dade Heritage Trust — the group behind successful efforts to save the ancient Miami Circle, the 1925 Freedom Tower and the modernist Miami Marine Stadium — has a strong case for the Herald building’s designation by the city Historic and Environmental Preservation Board, which has authority to confer legal safeguards on meritorious places and buildings.

But the designation could throw a monkey wrench into plans unveiled recently by the Genting group — which paid $235 million for the Herald building and 10 acres of surrounding parking lots — to demolish the 1963 structure and erect a massive gaming resort on the land if the Legislature approves a casino bill.

Historic designation — which under longstanding law can be imposed regardless of Genting’s wishes — would bar demolition of the building or significant alteration of its exterior, possibly including the neon sign spelling out the newspaper’s name, though it would allow additions. Designation could also cover the building’s soaring lobby if it’s considered integral to its architectural merit.

Supporters of designation say they expect the application will prove highly contentious, but argue the building’s distinction as an exemplar of Miami Modern architecture (dubbed MiMo), its iconic presence for five decades at the foot of the MacArthur Causeway and the extensive influence of the newspaper and its leaders on Miami’s history make it a slam-dunk case on the merits.

“It may be an uphill a battle, but it’s a worthwhile undertaking,’’ said Heritage Trust chief executive Becky Roper Matkov after the group’s board voted to proceed with the application, which is now being drafted. “I’m sure we will have a lot of opposition from monied interests. That hasn’t stopped us before.’’

In a statement to The Herald, Christian Goode, president of Genting’s Resorts World Miami subsidiary, called the Herald building “an affront to smart urban planning’’ because it blocks views of and public access to Biscayne Bay. Genting’s plans call instead for a wide public baywalk.

“Any impacts derived from preserving the Herald building are far outweighed by the benefits that a new master-planned development will bring to the Omni neighborhood, including activating the downtown waterfront, employing tens of thousands of Floridians, generating meaningful tax revenue and adding value to a depressed area,’’ Goode’s statement said.

The newspaper, which as part of the Genting sale will occupy the building until 2013 rent-free, has no say in the site’s redevelopment or historic designation of the structure.

The Trust’s application would receive preliminary consideration from the city’s preservation board Feb. 7. If the board votes to take it up, the proposal would be slated for a second, in-depth hearing. Board decisions can be appealed to the city commission, and further challenges would go to state courts.

Matkov emphasized that designation would do nothing to block gambling on the site. Though it would require Genting to integrate the building into its plans, the Malaysian gaming giant could still build on the balance of the Herald property, and in fact could erect a tower over the existing building, they say.

“Could this building be incorporated into a casino? Of course it can,’’ said planner Randall Robinson, co-author of MiMo: Miami Modern Revealed, which features the Herald building. He was not involved in the Heritage Trust decision.

That decision came after considerable debate within the Trust. Two board members, asking not to be named, said they’re concerned the group is overreaching and risks generating a backlash against preservation.

The Trust’s application, and the support of several leading Miami preservationists, marks a significant change in public attitude towards the Herald building, once widely derided for its boxy 1960s design and the modern architecture style it represents. Preservationists have increasingly embraced the nation’s mid-20th century architecture as it reaches 50 years of age — typically the minimum age for landmark status.

The Herald building has grown in estimation amid the recent popularization of Miami’s tropical-modern architecture, along with two prominent structures built at the same time: the Bacardi complex on Biscayne Boulevard and the Miami Marine Stadium, both now designated historic. The city has also designated 30 blocks of the Boulevard, which include numerous MiMo buildings, and Miami Beach has created historic districts around its iconic MiMo hotels, including the Fontainebleau and Eden Roc.

Fans of the Herald building cite its dramatic entryway, fine modern detailing and use of rich materials inside and out, including marble, granite, mosaic tile, glass and metal.

“This was high craftsmanship,’’ Robinson said.

Because preservation hearings are quasi-judicial proceedings, they must follow rules of evidence that could favor proponents of designation, some experts say. To declare a site historic, proponents must show it meets criteria established by the U.S. Department of the Interior, including architectural importance and association with historically significant figures and events.

If those requirements are satisfied — and supporters say the Herald building clearly would — under the law, the board and commissioners are supposed to approve designation, several experts said. There would be one additional hurdle: Because the Herald building, like the Bacardi buildings and Marine Stadium, is just short of the 50-year threshold, proponents would have to demonstrate extraordinary merit.

“There’s just one issue: Does it meet the criteria?’’ said historian Arva Moore Parks, former chairwoman of the city’s planning board, who supports the designation. “Then you have to follow the law.’’

The Herald building, the largest structure in Florida when it opened, was designed by a prominent Chicago firm, Naess and Murphy, also responsible for the similar Sun-Times building, which was recently demolished. The building, which includes a printing plant, was erected on the bay because newsprint was delivered by barge, but also to make a statement about the newspaper’s prominence in city affairs.

The building also housed the Miami News and served as national headquarters for Knight Ridder, the now-defunct newspaper chain founded in part by brothers John S. and James L. Knight. For decades the company chairman, the late Alvah Chapman, Jr., exercised an outsized civic role in Miami.

The newspaper won 19 of its 20 Pulitzer prizes while there, several of them for investigative series that influenced the course of local events.