Fifteen senators led by Sen. Joseph I. Lieberman (I-Conn.) have introduced a resolution saying that the Syrian government has “lost legitimacy” because of its violent suppression of protestors and calling for more sanctions against Syrian President Bashar al-Assad.

At a Capitol press conference Wednesday, Lieberman and co-sponsor Sen. John S. McCain (R-Ariz.) said they did not see a need for U.S. military action in Syria at the moment. Unlike in Libya, they said, the Syrian opposition has not asked for U.S. military support, and there was little evidence that Syrian air power was targeting protestors.

“There is not a military answer to that question right now,” Lieberman said. “But I would not want Bashar al-Assad in Damascus to feel comfortable — if he continues to rampage against his own people--that it’s impossible that the world will rise up and strike back.”

The resolution calls on President Obama to “speak out directly, and personally, to the people of Syria about the situation in their country.” It also calls for economic sanctions to be extended to more members of the Syrian elite, including Assad himself.

“Assad is a thug and a murderer — a totalitarian leader who is pursuing the Gaddafi model and hopes to get away with it,” Lieberman said, meaning Libyan leader Moammar Gaddafi.

Lieberman and McCain were joined at the podium by Sens. Benjamin M. Cardin (D-Md.) and Marco Rubio (R-Fla.). Rubio, a freshman senator making one of his strongest statements yet on foreign policy, spoke about the universal nature of human rights. He was the most specific of the senators about what Assad’s fate should be, suggesting that “patriots” in the Syrian armed forces might remove him from power in a coup d’etat.

“Bashar al-Assad should no longer be treated as the legitimate ruler of Syria,” Rubio said.