The Muslim Brotherhood in Jordan

Admiral Mike Mullen, chairman of the U.S. military's Joint Chiefs of Staff, traveled to Jordan this month for talks with King Abdullah II, just days after the monarch swore in a new government and promised to implement economic reforms. Admiral Mullen appeared to be in the region to reassure the jittery kingdom that the U.S. has its back.

But if today's volatile Middle East is the new normal, Admiral Mullen's presence may do little to prevent instability in Jordan. Contagious political protests have emboldened the monarchy's existing opponents. For the first time since “Black September,” when Palestinians tried to hijack the country in the early 1970s, a small but growing group of anti-regime Jordanian activists openly seek to end the monarchy. Their new websites allege human-rights abuses, corruption, and worse. Meanwhile, 36 influential tribal patriarchs have warned of an uprising if the King's wife Queen Rania, who is of Palestinian descent, continues to build “power centers” that threaten the traditional Hashemite leaders.

But it is Jordan's Muslim Brotherhood, known as the Islamic Action Front (IAF), that may be best poised to stir up popular unrest. In Jordan, as in Egypt, these Islamists are well organized. The king, seeking to stave off a crisis, met with the IAF earlier this month for the first time in nearly a decade. The group opposes the king's recent appointment of Prime Minister Marouf al-Bakhit, who they rightly note does not qualify as a reformer. More importantly, the IAF seeks to amend Jordan's election laws. This is where King Abdullah skates on thin ice.

If the law is amended, the IAF could regain significant parliamentary power, and possibly even a majority. The IAF could then challenge secular Jordanian laws, the king's economic ties with the U.S., and Jordan's unpopular peace with Israel.

Then again, if the king keeps the country's election laws as they are, the IAF could intensify its protests and prompt the King to suppress them with force, thereby weakening the regime's credibility and international standing.

Jordan's Brotherhood, founded upon the same totalitarian ideology as the Egyptian branch, emerged in 1945. During the 1950s, amid challenges from pan-Arabists, Communists, and internal political threats, King Hussein welcomed the Brotherhood as a “loyal opposition.” The group's popularity surged after the 1967 Six Day War and the 1979 Iranian Revolution, mirroring trends across the Arab world. The Brothers created a network of social and welfare institutions, mosques, and religious centers.

The dynamic changed in the mid-1980s, when Jordan's Brotherhood participated in anti-regime protests. After years of allowing the Brotherhood to penetrate Jordanian society, King Hussein grew alarmed. He responded with increased repression, imprisoning some of the Brotherhood's leaders and more stringently monitoring their activities.

By 1989, the King decided to take a strategic gamble and held parliamentary elections. He hoped to co-opt the Brotherhood by making them play by the rules of a democracy. The Brotherhood accepted his challenge, and ran candidates under the global Muslim Brotherhood banner of “Islam is the Solution.” Through Jordan's bloc-voting system, where voters cast as many votes as there were seats in his district, the Brotherhood won 22 out of 80 seats, making it the largest single bloc in the Jordanian parliament's lower house. Other political Muslims won 14 seats, giving Islamists a total of 36 seats in the house.

With Islamists thus amply represented in parliament, domestic considerations hampered the king's foreign-policy decision making. During the 1991 Gulf War, the king declared neutrality, while the Brotherhood backed Saddam Hussein. Relations soured further when King Hussein participated in the Madrid peace talks between the Palestinians and Israelis. The Brotherhood declared a day of mourning when the talks opened in October 1991.

Ahead of the 1993 elections, in an effort to weaken the Brotherhood, the king forbade parties with formal political ties abroad. The Brotherhood circumvented this by renaming its political arm the “Islamic Action Front.” Again they ran on the slogan “Islam is the Solution,” while advocating the implementation of Sharia law and rejecting normalization with Israel.

But the king made one more addendum targeting Islamist power, in 1993 replacing Jordan's voting-bloc system with a “one man, one vote” system. In addition, the king banned public rallies and mosque sermons. In the end, the IAF secured 16 of 80 seats, with another six seats going to Islamist independents. Islamists still held the largest bloc in the lower house, but had lost ground.

Ahead of the 1997 elections, the IAF threatened a boycott if the king did not meet certain demands. They sought to repeal the “one man, one vote” policy, ease media restrictions, enhance parliamentary authority, implement economic policies free of Western influence, and reject Jordan's 1994 peace treaty with Israel. When King Hussein balked, the IAF boycotted the election.

King Hussein died in 1999, bringing his son Abdullah to the throne. Ties between the new monarch and the IAF have remained uneasy. Through his father's election laws, King Abdullah has kept the Islamists in check. In 2003, the IAF took only 20 out of 84 seats, and in 2007, that number dropped to six.

Now, with the Middle East on tilt, the IAF has new leverage. If King Abdullah reinstates Jordan's old elections laws, the Islamists will enjoy new parliamentary power. If the king demurs, their power on the street stands to grow. It's hard to see how the handshake of an American Admiral will improve King Abdullah's options.

Mr. Schanzer is vice president of the Foundation for Defense of Democracies.