The Obama administration needs to get tougher on Iran if it wants to broker peace in the Middle East, Sen. Joseph Lieberman (I-Conn.) said Wednesday.

The Senate Armed Services Committee member also reiterated his support for tough economic sanctions against Tehran, which he argued was the only way to show President Mahmoud Ahmadinejad that the United States was serious about nuclear non-proliferation.

"The original Obama administration position seemed to suggest the biggest obstacle to peace in the Middle East was the Israeli policy of building on territory [believed to be Palestinian]," Lieberman told MSNBC. "The real threat to peace in the Middle East is Iran."

"If you look at our policy, which is a global policy, to stop the Iranians from building nuclear weapons, everything we have done thus far has failed," Lieberman added, noting that he was preparing a bill that would levy new economic sanctions on the country. "I think the only way we're going to stop this development... is for us to make it clear to the Iranians that if they don't stop, they'll suffer."

As Lieberman voiced his concerns about U.S. policy toward the Middle East state, U.N. General Assembly members prepared to host Ahmadinejad, who will deliver a speech to the body on Wednesday afternoon. A number of delegates, including those from Israel, have already signaled they will not attend the speech. While it is unclear whether U.S. leaders will join them, the State Department did announce last week that Obama would not meet with the Iranian president directly.