U.S. Congress has moved closer to passing legislation that would limit President Donald Trump's ability to wage war against Iran. But he can still veto it, and its unlikely that enough Republican lawmakers would flip sides to stop him. The Senate on Wednesday (February 12) advanced the bill known as the Iran War Powers Resolution. If enacted, it would mean that the president cannot order the military to engage in any hostile acts with Iran except in clear cases of self defense. Otherwise it would require the express authorization of lawmakers, such as if Congress declares war. The Constitution says that only congress can declare war, not the president. Eight Republicans joined Democrats in supporting the resolution, A final vote is expected later this week. Trump says the resolution would send the wrong message to Tehran. He tweets, quote, "We are doing very well with Iran and this is not the time to show weakness." Supporters disagree.