One of Donald Trump’s staunchest conservative opponents said Saturday he’s had a change of heart. Bill Mitchell, an influencer with a large social media following, previously endorsed Ron DeSantis for the nomination. In fact, Mitchell went a step further, suggesting he would delete his account if Trump ends up being the nominee for the GOP. “Unless DeSantis wins the GOP nomination, I will quit social media and politics forever,” Mitchell posted in June. “I can no longer work in a world where a narcissistic, lying, criminal like Trump is my party’s nominee.” On Saturday, however, Mitchell had a…