Several senior members of Congress wrote US President Barack Obama Thursday urging that he set a deadline for engaging with Iran and that he apply strong sanctions if talks don't work. The lawmakers, who included House Majority Leader Steny Hoyer (D-Maryland) and House Foreign Affairs Committee Chairman Howard Berman (D-California) also called for the US to immediately begin both to talk to Teheran and to rally allies to impose sanctions should the outreach not convince Iran to halt the enrichment of uranium. The Obama administration has been reviewing its Iran policy since taking office, and while it has made some modest moves - sending a New Year's greeting to the Islamic republic, inviting Iran to a UN-led conference on Afghanistan next week and renewing sanctions that have been in place for years - officials have not outlined its approached or made large gestures. Some observers worry that any active engagement in the near term could affect the outcome of elections in June, where Iranian President Mahmoud Ahmadinejad is facing challenges from more moderate candidates. At the same time, Israel has indicated it believes the time frame for stopping Iran from making a nuclear weapon is limited, and that talks should start, and likely end, quickly. The letter from the members of Congress seemed more in line with that thinking. "Engagement must be serious and credible, but it cannot be open-ended," they wrote. "If we truly mean that Iran cannot be allowed to possess nuclear weapons, urgent action is required today. We must use the time available to us to begin engagement and to convince the Iranians of our seriousness of purpose. Otherwise, we will face far more difficult decisions in the future." They also warned, "We cannot allow Iran to use diplomatic discussions as a cover for continuing to work on its nuclear program. Iran must verifiably suspend its uranium enrichment program within at most a few months of the initiation of discussions." Failing that, they listed a series of steps the administration should take, including sanctioning international banks that do business in Iran and energy companies that invest in Teheran's oil sector, as well as insurance companies that facilitate Iranian trade. They also recommended that ships calling on Iranian ports be denied access to American ones. Though some of those sanctions would be unpopular with international partners, the congressmen stressed the importance of working with allies and other major powers, urging Obama to make Iran the top issue in dealing with Russia and China.