Microsoft is working to put a dent in Amazon’s dominance in the government agency cloud computing space, organizing its rivals to help.

Amazon’s AWS is the leading cloud provider platform, both in the private sector as well as the public. Microsoft is its largest rival, and the company is working on getting other companies to help lobby against Amazon’s dominance, according to a report in The Wall Street Journal.

Microsoft has been sharing talking points with cloud providers Google and Oracle, as well as IBM, VMware, Dell, and HP Enterprise. The talking points are aimed at lobbying Washington to require a multi-vendor approach for large cloud contracts. According to WSJ’s sources, Microsoft has not included Amazon in its efforts.

Read more: Microsoft Azure Is a Major Threat to AWS

There’s certainly no love lost between Amazon and Microsoft, especially in their battle for the cloud market. Microsoft famously scored the Pentagon’s JEDI contract, worth some $10 billion, only to have Amazon relentlessly challenge the win in court until the Department of Defense was forced to abandon the contract in an effort to move forward with its cloud transition.

Not long after, AWS won a $10 billion contract to provide cloud services to the National Security Agency. Microsoft challenged that contract award but was unsuccessful in overturning the results.

More recently, an AWS exec took Microsoft to task over its cloud licensing terms, accusing the company of not putting customers’ needs first and engaging in anti-competitive behavior.

It appears the rivalry between Microsoft and AWS is picking up steam with no end in sight. If Microsoft is successful in rallying the smaller cloud providers to its cause, it could represent the single biggest threat that AWS has ever faced.