WASHINGTON (AP) — Labor unions are gearing up to spend more than $400 million to help re-elect President Barack Obama and back other Democrats at the federal and state level in a fight for labor's survival.

Union leaders say they have little choice as they try to beat back GOP efforts to curb collective bargaining rights or limit their ability to collect dues.

The nation's largest public employee union has already spent $1 million on television ads aimed at weakening GOP presidential hopeful Mitt Romney, the candidate they expect to win the nomination.

But union resources are being spread thin after they spent millions last year to fight anti-union measures in Ohio, Wisconsin and other states. They are also spearheading a recall of Republican Wisconsin Gov. Scott Walker.