We've lowered marginal tax rates multiple times, and it never produces more revenue. Even the most ardent supply-side economists don't believe that tax cuts fully pay for themselves (they believe only a fraction of lost revenues are offset by supply-side effects).
... virtually all mainstream Republicans are now complete crackpots. Which goes a long way toward explaining why the Republican party's budget proposals make absolutely no sense. How can you craft a coherent budget when your only idea for raising revenue is to massively cut revenue?
Republicans will point to rising government revenues in the years following the Bush tax cuts for the super rich. They conveniently overlook the fact that every year the population increases and, at least outside of recession, the economy grows every year. Tax cuts have nothing to do with the increased revenue. You can't turn down income and expect more income. Unless you're a crackpot.