The New York Public Library is engaged in a public-relations blitz to address criticism from scholars and writers who object to the library’s plan to reimagine its Fifth Avenue flagship building at an estimated cost of $300 million.


In the past few weeks the library’s president, Anthony W. Marx, has written articles for The Huffington Post and Inside Higher Ed, appeared on radio and television and assembled an advisory panel that includes people skeptical of the plan.


The library’s efforts are the sort of salesmanship that traditionally accompanies any new ambitious undertaking. But they are also an acknowledgment that the plan, which includes the sale of two prominent Manhattan branches, is a dramatic reshaping that has, at the very least, upset library traditionalists.


Several scholars have published criticisms of the project, known as the Central Library Plan. On Friday others began circulating a letter of protest among academics; more than 200 have signed so far, including Mario Vargas Llosa, the Nobel Prize-winning writer, and Lorin Stein, the editor of the Paris Review. “We are alarmed by the Central Library Plan, which seems to us to be a misplaced use of funds in a time of great scarcity,” the letter says. “We think the money raised can be better used to preserve and extend what already exists at 42nd Street.” Mr. Marx said the issues raised by critics would be considered. “The scholarly community is concerned and we are concerned,” he said.


The project would convert the main library, now strictly a reference operation, into a hybrid that would also contain a circulating library, many computer terminals and possibly a cafe. The Mid-Manhattan branch and the Science, Industry and Business Library would be sold and their operations folded into the main building. To accommodate the new services, up to half of the three million volumes in the stacks under the main reading room would be moved into storage in New Jersey.


Critics say that the money would be better spent refurbishing deteriorating branch libraries, and that the changes will diminish the library’s role as a leading reference center, essentially turning it into a glorified Starbucks. Of particular concern: how long it will take the library to retrieve books from storage.


“The library is being repositioned less as an institution that thinks of research and scholarship than as a kind of fashionable place for intellectuals that is more about entertainment than depth of knowledge,” said Ilan Stavans, a professor in Latin American and Latino culture at Amherst College, where Mr. Marx was formerly president.


“Research is going to pay a heavy price with this change,” he added.


Monica Strauss, an art historian, said: “The age of the book is not yet over. It may be over in 40 years, but it’s not over now.”


Mr. Marx said in an interview that the plan — which had languished due to the economic downturn — incorporates a continuing commitment to books and research and represents an effort to meet the needs of the general public better.


“The project will produce a greater single facility that includes the crown jewel of the branch system — Mid-Manhattan,” Mr. Marx said. “People come from all over the city now to use the library, and the system will end up with significant additional resources.”


Renovating just Mid-Manhattan, as some have suggested, would cost about $150 million and require closing the library for about two years, Mr. Marx said; selling it, along with the science library, will infuse the system with $10 million to $15 million in annual operating savings that can be spent on other priorities, like research acquisitions.


“We see this as an investment in the research collection,” Mr. Marx said.


Designed by the British architect Norman Foster, the renovation is to be financed with $150 million from the city, proceeds from the sale of the two libraries and private donations.


Joan Scott, a social science professor at the Institute for Advanced Study, who helped draft the letter of opposition, called the plan disturbing.


“The idea that these reforms are going to make it more democratic doesn’t make sense to me,” she said.


Critics question how users of the libraries to be sold will fit inside the main building (its number of annual visitors — 1.6 million — is expected to more than double) and whether books moved to New Jersey really will be available within 24 hours, as the library has promised. Off-site books currently often take longer than that to obtain.