I think it is because she is a weapon for the republicans in elections. Every Democratic candidate in Georgia had ads running against them saying they were supported by Pelosi and her liberal agenda. And here in Georgia, "a liberal agenda" is the absolute worst thing a politician can be connected to. Even if the "liberal agenda" is you support health care for those with pre-existing conditions.==============================

He wants to be able to rail against Pelosi every chance he gets.  A different speaker would require re-educating the base.