Final answer:
The president's power to veto bills that have been passed by both the House and Senate serves as a check by the executive branch on the legislative branch.
Step-by-step explanation:
Among the executive branch's checks on the legislative branch is the president's power to veto bills that have been passed by both the House and Senate. When Congress passes a bill, the President has the option to approve the legislation by signing it or to check the legislative process by using the veto power. In the event of a presidential veto, Congress may attempt to override the veto by securing a two-thirds supermajority vote in both chambers, which serves as a check within a check between the legislative and executive branches.