Even Republican senators are opposed to Trump's transgender ban:

"Dan Sullivan (R-Alaska), who served in the Marines: “I’m all about training standards. High, high standards for whoever joins the military,” he told HuffPost. “But my initial reaction is, if you can meet those standards, we shouldn’t care who you are. So, meet the standards, and you should be able to join the military.”

Sen. Joni Ernst (R-Iowa), a former Army Reserve commander and the first female combat veteran elected to the Senate: “While she believes taxpayers shouldn’t cover the costs associated with a gender reassignment surgery, Americans who are qualified and can meet the standards to serve in the military should be afforded that opportunity,” 

Sen. Orrin Hatch (R-Utah), who is up for reelection in one of the reddest and most socially conservative states in America: "I don't think we should be discriminating against anyone. Transgender people are people and deserve the best we can do for them."