I spent much of the last year of my term in office talking about Iran. Whether because of its role as the prime sponsor of Islamic terrorism in the world - the creator of Hezbollah and the driving force behind Hamas - or as the chief foreign-power obstacle to a peaceful, democratic Iraq, Iran is our greatest national security concern.

Much is being made of the new National Intelligence Estimate (NIE) that Iran, under pressure from economic sanctions, stopped its nuclear program in 2003. That same report, however, states that Iran is continuing to enrich uranium at a pace that would result in weapons-grade nuclear material by 2010 to 2015. Iran also announced last month that it had developed a missile that could deliver a nuclear warhead to Jerusalem. And Iran's negotiators last week in London announced that all past proposals to limit Iran's nuclear program were irrelevant and that further talk of curbing its uranium enrichment was unnecessary.

We must view this information in light of the continued obsession of Iranian President Mahmoud Ahmadinejad with the return of the Twelfth Imam. That's the ninth-century Shiite leader who, according to his view of Shiite theology, will return to earth to lead them after an Armageddon in which Islam has conquered Christians and killed the Jews. The Iranian president continues to maintain that one of the foundational reasons for the creation of Israel, the Holocaust, never happened, and he marked the occasion of last week's Mideast summit in Annapolis by again threatening Israel. Nice.

A consensus has developed that a nuclear-armed Iran would be our greatest national security challenge since the end of the Cold War. The NIE assessment also tends to support the consensus that a combination of economic sanctions, diplomacy and support for pro-democracy groups can be effective in getting Iran to give up its nuclear ambitions.

That is why I introduced the Iran Freedom Support Act in 2004. This bill became law last year. It funds pro-democracy groups and imposes tighter sanctions on Iran. Last month, the Bush administration, using authority granted in this new law, imposed the toughest sanctions against Iran to date. These sanctions are designed to make it more difficult for non-U.S. companies to do business with Iran - and pressure the regime to begin serious talks on ceasing its drive to acquire nuclear weapons. They've also contributed to the economic woes that have damaged the regime's popularity.

It's vital that we put aside politics to find new and effective ways to confront Ahmadinejad and Iran's mullahs. As one presidential candidate recently stated: "The Iranian government uses the billions of dollars it earns from its oil and gas industry to build its nuclear program and to fund terrorist groups that export its militaristic and radical ideology to Iraq and throughout the Middle East."

Rudolph Giuliani? Mitt Romney? Fred Thompson? No, it was the can't-we-all-get-along candidate, Barack Obama.

While Americans have been prohibited from direct commercial transactions with Iran for decades, many foreign companies, particularly European energy firms, still do business with the Iranian regime. Thus, they are supporting, at least indirectly, Iran's quest for a nuclear weapon. The problem is that many U.S. mutual and pension funds invest in these foreign companies. The solution is what's happening in many states: passage of laws requiring that their state funds, particularly their pension plans, not invest in companies that do business in Iran.

Last summer, I campaigned with Missouri Treasurer Sarah Steelman, who has led an effort to divest the Missouri State Employee Retirement System from companies doing business with nations that the U.S. State Department lists as state sponsors of terror. Missouri now has a terror-free investment fund for its public employees and for investors in the state's college-savings program.

Since adopting a terror-free investment policy, the Missouri Investment Trust's performance has actually improved, outperforming a benchmark index by a substantial margin. And, last month, despite opposition from California's profit-fixated fund managers, Gov. Arnold Schwarzenegger signed legislation to require the state's pension fund - the nation's largest - to divest of companies doing business with Iran. You can count on Ahhnold to keep going after the bad guys.

Thanks to Pennsylvania state Rep. Josh Shapiro (D., Montgomery), our legislature is getting into the act. He's sponsored three divestment bills (HB 1085, HB 1086 and HB 1087) now making their way through the state House. Soon, the Appropriations Committee will consider his efforts to pull $10 billion in state-managed funds out of companies doing business in nations designated as state sponsors of terrorism.

Gov. Rendell and our legislators have a great opportunity to help defeat our enemies and potentially save thousands of lives. They should seize it now! As Shapiro says, "Our commonwealth must use its economic might to stand with our allies, isolate our enemies, and help win the war. Divesting from terror-sponsoring nations is the best way to accomplish these objectives."