Thoreau did not think very highly of voting in general or individuals who expressed their opinions by casting votes. He thought that voting was too much like gambling: risky and uncertain. He said that many people have opinions that seem strong. However, he thought that people often did not do enough...
to actually remedy the social or political ills they witnessed. Although they might regret that some policy or institution exists, they did not take any real effective action to curb or banish it. He says the following inCivil Disobedience:
They will wait, well disposed, for others to remedy the evil, that they may no longer have to regret.
In other words, these individuals may wait in the hopes that their government will actually cure the problem. Further,
At most, they give only a cheap vote, and a feeble countenance and God-speed, to the right, as it goes by them.
Thus, Thoreau paints voting as tantamount to a prayer: there is a chance that one might get what one wants, but there is just as significant a chance that what one wants to happen will not actually happen. The more effective way to achieve change is to actually get one's hands dirty and do the work oneself. People who only vote are doing no work to actually change anything.