If you want labor's support, you need to do something for labor.

2012:

The AFL-CIO has told Washington Whispers it will redeploy funds away from political candidates smack dab in the middle of election season, the latest sign that the largest federation of unions in the country could be becoming increasingly disillusioned with President Obama. 

The federation says the shift has been in the works for months, and had nothing to do with the president's failure to show in Wisconsin last week, where labor unions led a failed recall election of Governor Scott Walker.

Barack Obama, 2007:

"If American workers are being denied their right to organize and collectively bargain when I’m in the White House, I’ll put on a put on a comfortable pair of shoes myself. I’ll walk on that picket line with you as president of the United States.”