which person introduced these modifications?
Senator John W. Bricker
Bricker Amendment
 Senator Bricker was influenced by the ABA's work and first introduced a proposed constitutional amendment in 1951. 
what is bricker amendment? It is the collective name of a number of slightly different proposed amendments. can you mention a few of those amendments? It declared that no treaty could be made by the United States that conflicted with the Constitution, It also limited the president's power to enter into executive agreements with foreign powers.
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Bricker Amendment [SEP] Introduction
Frank E. Holman, president of the American Bar Association (ABA), called attention to Federal court decisions, notably "Missouri v. Holland", which he claimed could give international treaties and agreements precedence over the United States Constitution and could be used by foreigners to threaten American liberties. Senator Bricker was influenced by the ABA's work and first introduced a proposed constitutional amendment in 1951. With substantial popular support and the election of a Republican president and Congress in the elections of 1952, together with support from many Southern Democrats, Bricker's plan seemed destined to Pass Congress by the necessary two thirds vote and be sent to the individual states for ratification by three fourths of the state legislatures.