Bank stocks got a huge lift on Friday, when lawmakers reached a compromise on watered-down financial regulation that will have a much smaller effect on their balance sheets than originally anticipated. However, banks can't breathe a sigh of relief just yet. A push to pass the Employee Free Choice Act, or "card-check," may be coming later in the year. As Senator Tom Harkin (D-Iowa) told the The Hill, "To those who think it's dead, I say think again."

Ironically, the Employee Free Choice Act actually does just the opposite. The bill would take away an employee's right to vote by secret ballot on whether or not to join a union, and allow union organizers to secretly target units within an organization in an attempt to persuade a majority of workers to sign authorization cards in favor of unionizing. This would force employers to enter into negotiations with union organizers.

The bill is important for unions with extremely underfunded multi-employer pensions. It would force newly unionized employers to enter these funds, taking away the employees' choice to instead put their funds in tax-deferred retirement accounts such as a 401(k).

In particular, union organizers are targeting tellers and other employees of large banking centers. Banks with large consumer businesses, such as Bank of America (NYSE: BAC), Citigroup (NYSE: C), and Wells Fargo (NYSE: WFC), will likely be most affected. Unionization would clearly increase employee costs, but union supporters argue that it will help deter the risky lending practices that almost sunk these same banks during the financial crisis. They argue that employees will feel less pressure to sell products to customers that these customers do not understand or cannot afford.

Card-check is a hot-button issue certain to garner much debate in the months ahead. What are your thoughts on the bill? What other stocks do you think will be affected by this legislation? Sound off in the comments box below.

Andrew Bond does not own shares in the any of the companies mentioned   Try any of our Foolish newsletter services free for 30 days. The Fool has a disclosure policy.