Back in the early days of voting in America. It was often a very intoxicating affair. In fact alcohol was often served at the polling and voting centers to get the crowds to come out. The candidate who provided the best and most alcohol was usually elected.
George Washington learned early on to have lots of alcohol available for all who wanted to vote. He used that ploy from his earliest days in running for various positions in Virginia. He was not alone, it was a common practise. One also has to remember that drinking was not uncommon in the early days of this republic. Most people drank, and many drank quite heavily.
Think of the some of the campaign slogans. Such as the "Hard Cider Candidate".... William Henry Harrison. The hard cider ran like water in that campaign. So in this painting you see the voting going on and drinking going on right with it.
Maybe they had the right idea. With some of the people running for office these days, you have to be drunk to vote for them! Really drunk!