Congress can use its power of the purse primarily to influence the agenda of the executive branch by controlling the funding of programs, agencies, and initiatives. Among the provided options, the statement that best captures this influence is:
"Congress could stop programs or plans proposed by the executive branch from being implemented."
By withholding funding or attaching conditions to funding, Congress can effectively impede or prevent the implementation of specific executive plans or programs. Additionally, Congress can encourage spending in certain areas by allocating funds to specific departments or initiatives, thus influencing the executive branch's priorities.