What clues from John C. Calhoun’s speech suggest that the sectionalist debate in the Senate was quite bitter at times? He states that institutions in the slaveholding states are hurting the Union. He claims that foreign nations will become hostile towards the US. He claims that free states will eventually become hateful, deadly, and hostile towards slave states.

He claims that free states will eventually become hateful, deadly, and hostile towards slave states.

Explanation:

John C. Calhoun´s last speech to the Senate was during the debate about the Compromise of 1850.  

Calhoun opposed the admission of California as a free state, warning about the North´s unfair exclusion of the South from new territories pushing the South to secede, by highlighting the growing hostility.