Amazon on Thursday said it planned to officially challenge the Pentagon’s surprise decision last month to award a $10 billion cloud-computing contract to Microsoft, setting off another legal battle over the lucrative, decade-long project.

Amazon said it had notified a federal court of its plans to protest the government’s decision. In a statement, a spokesman for the company suggested that the contract for the Joint Enterprise Defense Infrastructure project, known as JEDI, was awarded based on political motivations.

“It’s critical for our country that the government and its elected leaders administer procurements objectively and in a manner that is free from political influence,” said Drew Herdener, the Amazon spokesman, in the statement.

“Numerous aspects of the JEDI evaluation process contained clear deficiencies, errors and unmistakable bias — and it’s important that these matters be examined and rectified,” he said.