I think it generally helps to follow the money. The big money is in big business increasing the bottom line by lowering wages in the economy. They can do that by increasing the labor pool enough so that there is a critical mass of workers that will accept employment at a lower wage than the current market prevailing wage. That is why the minimum wage, for example was legislated in to action.
That is the commonly stated reason for the enactment of the minimum wage, the so-called 'baptist's reason' (in the bootleggers and baptists paradigm [1]). Historically the minimum wage has been used to discriminate against minorities and other targeted groups by making their wages higher than their value to an employer[2], this would be the so-called 'bootlegger's reason'.
edit: if you follow the money on the bootleggers side, you will see that unions and companies with high capitalization support increasing minimum wages.
Companies with high capitalization? What do you mean by that?
Some corporations support raising the minimum wage only in the sense that it would bankrupt their competitors business models. (cf Costco vs Wal-Mart). Although as someone in support of a higher minimum wage I don't see that necessarily as a bad thing.
Unions are less than 7% of the private sector workforce and shrinking, their influence has been quashed, for the most part ever since Reagan dismantled PATCO in 81.
Economically, a minimum wage sets a price floor for labor. At higher levels it also can induce demand by increasing the velocity of money through the bottom rungs of the labor force. Especially since the poor spend a much higher % of their income than the wealthy do.
And with respect to your [2], I counter with [0]. Minimum wage actually has very little if any empirical affect on unemployment.
