LANCASTER, Ohio — The national anthem was taking too long.

The Romney campaign’s advance team had precisely timed its rally at the town square here, charting the exact moment when the event’s backdrop, the municipal building, would be bathed in an alabaster glow from the setting sun.

Nearly two dozen lights were set, illuminating banners, flags and the square itself for the rally on Oct. 12. The day before, aides had taken photos of the site every 15 minutes as day dwindled to night, ensuring that Mr. Romney would take the stage — and cameras would click — at the proverbial golden hour.

Now all was in jeopardy.

The singer had thrown in a few extra little-known verses, pushing back the rally’s start time by several minutes. John Legittino, the director of production, realized the sun was lower than planned, and began dimming some of the 12,000-watt lights and turning others off.

“Let’s add one-half C.T.O. to four of the fixtures,” he said. (Translation: Add a warm orange filter to the lights, casting the stage in the same hue as the setting sun.) Moments later, Mr. Legittino nodded almost imperceptibly and headed over to the audio station to cue up the right song, “Born Free” by Kid Rock.