As Congress debates various gun control measures, President Obama is publicly putting the heat on Capitol Hill.

"The only way that we're going to be able to do everything that needs to be done is with the cooperation of Congress," he said Monday while hosting law enforcement officials from around the country.

But Supporters of tougher gun controls are growing increasingly worried lawmakers won't pass any substantial measures and have begun to focus their efforts elsewhere. A number of Obama allies across the country have called on public employee pension funds to divest of any holdings linked to the gun industry.

"City of Los Angeles pension funds should not go to profit companies that produce weapons designed to maximize carnage and death," Mayor Antonia Villaraigosa vowed.

Chicago Mayor Rahm Emanuel, a former Obama White House chief of staff, has made the same commitment and gone a step further. Emanuel has authored letters to Bank of America and TD Bank because they maintain multimillion-dollar lines of credit for major gun manufacturers. In the letters, Emanuel urges the banks to use their influence to "push" the manufacturers to go along with the president's tough new gun controls.

Lawrence Keane, general counsel for the National Shooting Sports Foundation, responded: "It's classic Rahm Emanuel Chicago politics -- try to bully and pressure our industry into somehow agreeing with the proposals that are being advanced by antigun mayors like him."

Sen. Ted Cruz, R-Texas, sent his own letter Tuesday, telling the banks, "Should Mayor Emanuel's bullying campaign prove successful, I am confident that there are numerous financial institutions in Texas that would be eager to earn your business."

Other gun control supporters are urging the president to use the "enormous" powers of the Executive Branch in order to go around Congress if necessary. Richard Aborn, once head of the Brady Campaign to End Gun Violence and now president of the Citizens Crime Commission of New York, says the move may be necessary because lawmakers are under extreme pressure not to pass new restrictions.

"The NRA knows how to mobilize," Aborn says, adding, "Their rhetoric will be extreme to scare their membership and they will threaten to take down any member that votes for in the affirmative for gun control."

A number of groups are also suing the Environmental Protection Agency in an effort to force it to regulate ammunition that contains lead. To date, the EPA has declined, but critics say that's because of political pressure from gun rights groups. The Center for Biodiversity is a party to the lawsuit, and its Senior Counsel Bill Snape says the move is only logical.

"We've gotten the lead out of paint, gotten the lead out of gasoline but for some odd reason, the EPA decided that, no, with lead bullets - that's okay," he said.