Fiat appeared willing to meet some or most of the government’s demands. But the company’s chairman, John Elkann, was intent on creating a company that would not be seen as politically influenced — a perception that had plagued the relationship between Renault and Nissan.

The board met one day this week. Then another. Sometime around midnight on Wednesday, French negotiators “pulled the elastic until it broke,” said one person close to the talks.

Nissan needed more facts

For 20 years, Renault and the Japanese automaker Nissan had a successful alliance sharing technology and design. Now automakers are facing disruption because of changing technology, environmental demands, and a fall in global sales. For legacy manufacturers like Renault and Nissan, alliances and mergers are essential.

But the architect of the Renault Nissan Alliance, Carlos Ghosn, was arrested in November on charges of financial misconduct. As he awaits trial, the automakers’ leaders — Jean-Dominique Senard, chairman of Renault, and Hiroto Saikawa, chief executive of Nissan — have been treating each other warily.

Initial talks between Renault and Fiat Chrysler were held behind Nissan’s back — the Japanese company said it was informed of the merger offer only hours before it was formally announced.

On Monday, the eve of the board’s first meeting, Mr. Saikawa issued a statement that seemed like a warning, saying that a Fiat-Renault merger would “require a fundamental review of the existing relationship” to ensure that the Japanese automaker’s interests were protected.

Nissan’s two representatives to the Renault board later said they intended to abstain if a vote were to take place immediately.