The SEIU has been at the forefront of taking on Wal-Mart, backing groups critical of Wal-Mart like Wal-Mart Watch.

FORBES: Magazine Article

For more than a year two union-backed groups, WakeUpWalMart.com and Wal-Mart Watch, have run a campaign against the Bentonville giant.

ECONOMIST: The store everyone, except shoppers, loves to hate

The SEIU has been at the forefront of taking on Wal-Mart (nyse: WMT - news - people ), backing groups critical of Wal-Mart like Wal-Mart Watch.

FORBES: Hill To Hear Union Concerns