Incidentally, Donald Trump was the only candidate who challenged Rubio’s premise, dismissing Obama as a rank incompetent. But whether or not you like what Obama has done, and none of the Republican candidates do, Rubio is correct that he has done an awful lot, transforming U.S. policy not only on health care, economics, financial regulation, and Iran, but also on energy, education, taxation, gay rights, Iraq, Cuba, and much more. Rubio’s opponents have dismissed him as a Republican version of Obama — charismatic and inspiring but ultimately too young and inexperienced for the job. Rubio was essentially implying, but not quite daring to say out loud, that Republicans need their own version of Obama to reverse what he’s done.