Mauro, a Polk County supervisor in a state where county supervisors are powerful figures, controls thousands of votes on the sprawling Italian South Side of Des Moines, almost all of them through absentee ballots. Decades ago, it occurred to Mauro that people didn't really like to go out and vote and that if you could make it easy for them, if you could get a ballot mailed to their home and then pick it up from them, that was a guaranteed vote. In the old days, absentee ballots had to be notarized (which meant that few people bothered with the process), but Mauro hadn't built up a successful insurance business by being dumb or lazy. He had an idea, and he and about 25 of his boyhood friends (who would become the nucleus of La Macchina) became notaries and carried the heavy seals around in their pockets as they went door to door collecting absentee ballots.
So let me start by saying that the concept that anyone in Des Moines controls "thousands" of votes is pretty absurd. I don't think it will come as an epiphany to most people to discover that south side residents are not sheep. They're Democrats. More of them are voting (and voting for Democrats) because people like John Mauro work to make sure more of them can vote.
On to the second part of the quote. I think the phrase "political machine" or "la macchina" or whatever you want to call it carries a negative connotation. One would think a political machine would steal elections, subvert the will of the voter, or engage in some other nefarious activity. I have yet to see any proof of wrongdoing on John Mauro's part. I've seen some accusations that led to nothing, but no actual wrongdoing.
So it appears, going all the way back to the days when John and friends carried notary seals from door to door on the south side, John Mauro has won elections by helping people vote. And if that's what a political machine is, then I'm glad we have one.