WASHINGTON (Reuters) - The U.S. Senate voted 55 to 41 on Thursday to advance the nomination of Federal Communications Commission Chairman Ajit Pai to serve a new five-year term heading the U.S. telecommunications regulator. The Senate is expected to vote Monday on final approval. On Thursday, Democrats criticized Pai for moving to dismantle Obama-era internet access rules and taking other steps to deregulate telecommunications rules. Pai won backing from Republicans for what they said was new openness and accountability to the agency and efforts to improve rural communications. 