Republican presidential hopeful Donald Trump is in yet another Twitter fight, this time with Saudi Prince Alwaleed bin Talal. "You are a disgrace not only to the GOP but to all America," the prince tweeted on Friday. "Withdraw from the U.S presidential race as you will never win." In response, Trump called Prince Alwaleed "dopey": "Dopey Prince @Alwaleed_Talal wants to control our U.S. politicians with daddy’s money. Can’t do it when I get elected." The Twitter spat comes at the end of a week in which Trump said Muslims should be banned from entering the country.