The president is a part of a political party and that party has certain views and opinions about certain issues like taxes and transit. Now when has to surround himself with like-minded people to ensure that he gets his decisions done and his laws/bills passed. So when he is faced with a hard decision, partisan or non-partisan support and opposition, he can't find people with different opinions or views on the issue because he had to create a like-minding group to ensure that normal political duties get through smoothly.