Mayor Fulop, who was running for re-election in heavily Democratic Jersey City, went public immediately with his opposition to hefty tax breaks for 1 Journal Square. The innovative aspects of the project were lost with the departure of WeWork, the city contends.

Since then, the Kushners have said that they will no longer use the federal program popular among developers that trades a path to citizenship to foreigners who invest $500,000 in American projects.

Last September, however, the planning board approved Charles Kushner’s revised plan for the project. In April, his company filed a new application for tax breaks and bonds from the city. But Mr. Fulop has remained publicly opposed to providing the Kushner project with any tax breaks, contrary to the mayor’s position on other projects, including Murray Kushner’s Journal Squared.

That left Mr. Kushner furious. He said that Mr. Fulop acknowledged last fall in a telephone conversation that Mr. Kushner was being discriminated against for his ties to the White House.

Asked about Mr. Kushner’s account of the phone call, the mayor’s office did not specifically address the matter. The mayor did point out that 1 Journal Square failed to start construction by Jan. 1, as required by the development agreement, and questioned whether Mr. Kushner has the financing to proceed.

“The Kushner project in Journal Square is in default for a number of project-related issues,” Mayor Fulop said in a statement, “not the family’s connection to the White House.”

Mr. Kushner acknowledged that Murray’s project, as the first big complex in Journal Square, deserved its generous tax breaks. But that doesn’t mean that he should get nothing, he said.

“We are front and center in Journal Square,” Mr. Kushner said. “We are certainly entitled to some sort of tax abatement for enhancing the area.”