LAS VEGAS — Clad in suits with earpieces, stained white kitchen garments and aprons, housekeeping skirts and pantsuits, the casino workers came to caucus as they can only in Nevada, breaking away from their jobs at midday Saturday to cast their votes not far from the craps tables.

But soon the workers found themselves squeezing royal blue “I’m with Her” shirts over shoulder pads and collars, quickly turning the right side of the caucus room into a sea of support for Hillary Clinton.

It was a sign of the muscular organization of the Clinton campaign, which helped carry it to a strong victory at this caucus site and a reassuring win statewide as the nominating contest heads to delegate-rich Southern states.