During the last four decades, precisely from the early 1970s, U.S. foreign policy has played a dominant role in the U.S. political landscape. The current political discourse is predominantly marked by divided government, polarized politics and gridlock. Such a contentious political environment has proved to be detrimental for efficient and effective policy-making in foreign policy. There are significant factors that profoundly complicate the process of decision making and congressional-presidential relations. Partisan and ideological differences under the conditions of divided government are dominant in the current political process and in turn affect the prospects of legislative-executive consensus and dissension. Other factors such as media salience, public opinion, and electoral imperatives also complicate the dynamics of legislative-executive relations. In an era in which heightened political brinkmanship has enveloped Washington politics, continuum of consensus and dissension between Congress and the president on strategic foreign policy issues has virtually become a norm. This dissertation examines the dynamics of legislative-executive relations in two high politics U.S. foreign policy issue areas of treaty process and war powers. It appears that in contemporary U.S. foreign policymaking the trajectory of a continuum of legislative-executive consensus and dissension is a new normal and potentially irreversible, as Congress and the president try ardently to preserve their respective constitutional prerogatives. Empirical investigation across these two issue areas demonstrates a new era of a resurgent Congress marked by its greater assertive role and acting as a consequential player in the foreign policy domain. The passage of the War Powers Resolution in 1973 by Congress, overriding a presidential veto, has profound implications in the modern political landscape. It was a pivotal moment that permanently transformed the future road map of congressional-presidential relations. Since then the U.S. political system has been relentlessly experiencing an institutional power struggle in the foreign policy domain. Findings suggest that when Congress determines to confront the president and exercise its constitutional responsibilities it becomes very difficult for the president to overcome such congressional resistance. Interbranch competition has virtually created a consistent trajectory of a continuum of legislative-executive consensus and dissension in the foreign policy decision-making process.