Hammam Saeed's comments were made at a protest outside the Egyptian Embassy in Amman, inspired by massive rallies in neighboring Egypt demanding the downfall of the country's longtime president, Hosni Mubarak.
About 100 members of the fundamentalist group and activists from other leftist organizations and trade unions chanted "Mubarak, step down" and "the decision is made, the people's revolt will remain."
Elsewhere, a separate group of 300 protesters gathered in front of the office of Jordanian Prime Minister Samir Rifai, demanding his ouster. "Rifai, it's time for you to go," chanted the group.
Jordan's protests have been relatively small in size, but they underline a rising tension with Jordan's King Abdullah II, a key U.S. ally who has been making promises of reform in recent days in an apparent attempt to quell domestic discontent over economic degradation and lack of political freedoms.
But as a monarch with deep support from the Bedouin-dominated military, Jordan's ruler is not seen as vulnerable as Mubarak or Tunisia's deposed leader. Even the Brotherhood - a fiery critic of Jordan's moderate government - has remained largely loyal to the king, who claims ancestry to Islam's Prophet Muhammad.
Many believe it's unlikely King Abdullah will bow to demands for popular election of the prime minister and Cabinet officials, traditionally appointed by the king.
Saeed said Arabs have grown disgruntled with U.S. domination of their oil wealth, military occupation of Iraq and Afghanistan and its support for "totalitarian" leaders in the region.
"The Americans and (President Barack) Obama must be losing sleep over the popular revolt in Egypt," he said. "Now, Obama must understand that the people have woken up and are ready to unseat the tyrant leaders who remained in power because of U.S. backing."
Saeed did not specifically name King Abdullah. But he said Jordan's prime minister "must draw lessons from Tunisia and Egypt and must swiftly implement political reforms."
"We tell the Americans 'enough is enough'," he said.
Rifai has in the last two weeks announced a $550 million package of new subsidies for fuel and staple products like rice, sugar, livestock and liquefied gas used for heating and cooking. It includes a raise for civil servants and security personnel.
Still, Jordan's economy struggles, weighed down by a record deficit of $2 billion this year, rising inflation and rampant unemployment and poverty.
