The judge hearing closing arguments this week for Staples' proposed $6.3B Office Depot merger seemed unimpressed by the company's defense against the government’s antitrust challenge of the deal.

Staples' lawyer Diane Sullivan argued that the deal was needed for the companies to compete with Amazon in the office supply space.

"This merger has always been about keeping these 1980s companies relevant in a digital world," she said. "They're (Amazon) like a boulder rolling down a hill."

But Judge Emmet Sullivan pushed back against Staples' arguments, highlighting inaccurate reasoning several times by the office supply giant's lawyers, Reuters reports.

The merger saga of the US's two largest office supply companies has been a work in progress—stretching back almost 20 years—and the FTC hasn't budged over antitrust concerns.

While Staples has offered to divest itself of a chunk of its contract business, in a similar way it did in Europe to gain approval, Judge Sullivan remains unconvinced, suggesting the case is still too close to call. [Reuters]