Billionaire developer Donald Trump, right, waits with his brother Robert for the start of a Casino Control Commission meeting…
FILE - Donald Trump, right, waits with his brother Robert for a meeting in Atlantic City, New Jersey, March 29, 1990. Robert Trump is seeking to block publication of niece Mary Trump's book about the Trump family.

A New York judge is temporarily blocking publication of a tell-all book that could be tremendously embarrassing to President Donald Trump. 

State Supreme Court Judge Hal Greenwald put on hold Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man, written by Trump’s niece, Mary Trump. Its publication date is July 28. 

Greenwald said he will make a final decision about publication after hearing the validity of a claim by the president's brother, Robert, who demands that Mary Trump abide by a family agreement not to write any books about the Trump family without permission of other family members. 

Mary Trump’s lawyer, Theodore J. Boutrous Jr., called the restraint on the publication a clear violation of the First Amendment.  

“This book, which addresses matters of great public concern and importance about a sitting president in an election year, should not be suppressed even for one day,” Boutrous said.  

Robert Trump’s attorney, Charles Harder, called the actions of Mary Trump and her publisher, Simon and Schuster, “truly reprehensible." 

“We look forward to vigorously litigating this case and will seek the maximum remedies available by law for the enormous damages," he said.   

Mary Trump is the daughter of the president’s elder brother, Fred Trump Jr., who died of a heart attack in 1981 after a struggle with alcoholism. 

Information about the book has already been taken down from Simon and Schuster’s website. The publisher called the book a “revelatory authoritative portrait of Donald J. Trump and the toxic family that made him.”