Vivek Ramaswamy ruled out a 2028 presidential run exactly once: one sentence, to one reporter, 18 months ago, before a single vote had been cast in Ohio. He has not said it again since becoming the Republican nominee for governor on May 5. He has good reason not to. The arithmetic of the next presidential cycle is brutal for a first-term Ohio governor, and he knows the numbers better than anyone — he ran them himself in 2023. What he promised In…