The SEIU today hosted protests outside eight major corporate industry associations that oppose the legislation. More than 300 workers from around the country were expected to participate, according to spokesman Jeff Cappella. SEIU's targets include the U.S. Chamber of Commerce, National Association of Manufacturers, National Restaurant Association, Business Roundtable and Retail Industry Leaders Association. The union supporters plan to meet with lawmakers on Tuesday to push the legislation.

EFCA would allow unionization if a majority of workers sign authorization cards and would eliminate a company's right to demand a secret ballot election. Proponents maintain that it allows workers to unionize more easily and freely, while opponents counter that union organizers will coerce individual workers to join and hurt small business.

These efforts come on the heels of AFL-CIO's winter meeting last week in Miami Beach, Fla., where both President Obama (via video message) and Vice President Joe Biden (in person) explicitly embraced the legislation.

SEIU's biggest rally today was planned for Lafayette Park, which borders the Chamber of Commerce's offices and the White House. This suits the chamber just fine, according to Justin Hakes, external affairs manager for the group's anti-EFCA campaign, the Workforce Freedom Initiative. "We're glad they're here," Hakes said. "First of all, it's exhibit A as to the kinds of pressure that individual workers will face if card check passes."

The chamber launched its own campaign this week by helping fly in 180 business leaders from across the country to meet with lawmakers. The group plans to follow up with TV and print advertisements in the business leaders' home states, and Hakes said the chamber will likely host a second round of guest advocates in April. The business group vowed to spend at least $10 million this year to fight the legislation, the Wall Street Journal reported.

                                                                                                                    --Amy Harder