While the parties were making their nominations for the Presidency, Sumner sought diligently for an opportunity in the Senate to give utterance to the sentiments of his party on the repeal of the Fugitive Slave Act. But not until late in August did he overcome the resistance of the combined opposition and gain the floor. The watchmen were caught off guard when Sumner introduced an amendment to an appropriation bill which enabled him to deliver a carefully prepared address, several hours in length, calling for the repeal of the law. The first part of this speech is devoted to the general topic of the relation of the national Government to slavery and was made in answer to the demand of Calhoun and his followers for the direct national recognition of slavery. For such a demand Sumner found no warrant. By the decision of Lord Mansfield, said he, "the state of slavery" was declared to be "of such a nature, that it is incapable of being introduced on any reasons, moral or political, but ONLY BY POSITIVE LAW.... it is so odious, that nothing can be suffered to support it but positive law." Adopting the same principle, the Supreme Court of the State of Mississippi, a tribunal of slaveholders, asserted that "slavery is condemned by reason and the Laws of Nature. It exists, and can ONLY exist, through municipal regulations." So also declared the Supreme Court of Kentucky and numerous other tribunals. This aspect of the subject furnished Sumner occasion for a masterly array of all the utterances in favor of liberty to be found in the Constitution, in the Declaration of Independence, in the constitutional conventions, in the principles of common law. All these led up to and supported the one grand conclusion that, when Washington took the oath as President of the United States, "slavery existed nowhere on the national territory" and therefore "is in no respect a national institution." Apply the principles of the Constitution in their purity, then, and "in all national territories slavery will be impossible. On the high seas, under the national flag, slavery will be impossible. In the District of Columbia, slavery will instantly cease. Inspired by these principles, Congress can give no sanction to slavery by the admission of new slave States. Nowhere under the Constitution can the Nation by legislation or otherwise, support slavery, hunt slaves, or hold property in man.... As slavery is banished from the national jurisdiction, it will cease to vex our national politics. It may linger in the States as a local institution; but it will no longer engender national animosities when it no longer demands national support."