Job Description ECS is seeking a Senior Proposal Manager, FEDSIM to work in our Fairfax, VA office. The Senior Proposal Manager, FEDSIM is responsible for shaping, structuring, and leading the lifecycle proposal development effort for proposals responding to AAS FEDSIM-managed federal procurements. This role sits at the intersection of proposal strategy, technical solutioning, and program design, as well as ensuring offerings are compliant, compelling, and aligned to both FEDSIM acquisition ex