This is an example of "senatorial courtesy".
Senatorial courtesy is a long-standing unwritten, informal, and nonbinding political custom (or protected tradition) in the United States portraying the propensity of U.S. legislators to help a Senate associate in restricting the arrangement to government office of a presidential candidate from that Senator's state.
Senatorial courtesy permits legislators of a proposed competitor's home state to dislike the chosen one because he or she may "personally obnoxious", or for comparable reasons. It is normal that the various representatives bolster the restricting congressperson's choice to veto the assignment, in order to get a similar courtesy consequently.
