From the San Francisco Chronicle:

Illinois Sen. Barack Obama - who has criticized Democratic presidential candidate John Edwards for benefiting from “independent expenditure” and political action committees - is taking heat because some of the same kind of organizations are now spending money, organizing and putting up TV ads on his behalf in the Bay Area.

These types of independent organizations aren’t illegal as long as they do not act in a coordinated way with the campaign. But critics say Obama is being hypocritical in denouncing Edwards’ connection with “527″ independent expenditure groups while not demanding that ones supporting him stop.

In Obama’s case, a 30-second TV spot financed by PowerPAC, a 501(c)(4) nonprofit political action committee, is running on cable stations in the Bay Area, urging change and a vote for Obama.

Obama spokeswoman Debbie Mesloh said Thursday that she believes Obama was not aware of the ad and that he has, in the past, expressed concerns about 527s and specifically Vote Hope.

527 groups are named after a section in the tax code which allows the formation of independent expenditure groups that can support candidates, ideas, causes and are not restricted by the same limitations as political campaigns. They cannot be linked directly with a political campaign.

Obama and his campaign have continually expressed their desire to see people not fund such groups and have attacked other candidates who have not taken public stands against spending when 527 groups work on their behalf. Some people are now asking that the Senator take a public stand and ask this group and others supporting his candidacy to stop spending.