Kuwait, a key U.S. ally in the Persian Gulf, is gripped by a deepening political crisis over demands for reforms that the ruling family is doggedly resisting.

The government controlled by the al-Sabah dynasty, which has ruled the oil-rich emirate for more than 250 years, has sought to head off trouble ahead of Dec. 1 parliamentary elections under new rules decreed by the emir that opposition groups will produce a rubber-stamp national assembly.

Kuwait has the most open political system in the gulf and is the only Arab monarchy in the region to have an elected Parliament.

Even so, it is far from free in the Western sense. Parliament's powers are limited and the political system can best be described as a semi-democracy.

The emirate has for years been gripped by a power struggle between the pro-Western al-Sabahs and a loose coalition of tribal nationalists and Islamists in the combative 50-seat National Assembly established in 1963.

Now the gulf state seems poised for a showdown between the ruling family and its youth-driven opponents who want to trim the al-Sabahs' power and bring in what among the gulf monarchies are considered sweeping constitutional changes.

What transpires in Kuwait could have a significant impact on the other monarchies in Saudi Arabia, the United Arab Emirates, Qatar, Bahrain and Oman and whether they will move toward greater democracy.

"The problem for Kuwait's ruling family with the escalating protest is that it could reach a tipping point where they're no longer in control of events," observed Kristian Coates-Ulrichsen, a gulf specialist at the London School of Economics.

"Change in Kuwait holds lessons for other gulf countries: Will it be incremental and consensual or will it be violent and forced?"

Already the Emirates, Bahrain and Oman are having to grapple with demands for political change to one degree or another. Like Kuwait, these monarchies have avoided direct confrontations with their subjects by buying acquiescence of the status quo with lavish public spending.

But the ruling families have made no real gesture toward reform and enfranchising their people, and public acceptance of autocratic rule and its cradle-to-the-grave welfare system seems to be wearing a little thin.

The political climate across the Arab world is forcing these hereditary monarchies to rethink their attitudes, and any major shift in Kuwait is sure to resonate around the most affluent region in the Arab world.

Kuwait's crisis began Nov. 16, 2011, when opposition supporters stormed Parliament demanding more authority for the assembly over the governments handpicked by the al-Sabahs.

In a February election, the opposition won 70 percent of the seats and pushed for a constitutional monarchy.

The big change was that tribal representatives held 20 seats, marking a distinct shift in the center of gravity of the opposition, until then dominated by urban politicians. The tribes no longer felt bound by fealty to the ruling family and, for the first time, openly challenged its power.

The Cabinet resigned June 25, the ninth to do so since 2006.

The 83-year-old emir, Sheik Sabah al-Ahmad al-Sabah, finally dissolved Parliament Oct. 7, claiming the popular Islamist-dominated legislature was unconstitutional amid rising tension triggered by what is seen as the most determined challenge so far to the authority of the al-Sabahs.

The opposition seemed likely to romp home again Dec. 1, but the emir, who's dissolved Parliament six times since 1963, ordered changes in voting districts that appear to favor al-Sabah supporters.

Street protests have been growing steadily larger, with opposition factions demanding a major crackdown on corruption, more accountability and that the ruling family relinquish its sweeping powers, including imposing al-Sabah-dominated Cabinets.

The emir, restored to power by a U.S.-led coalition after Saddam Hussein conquered Kuwait in 1990, was widely revered for many years. Most criticism of the royal family was aimed at other members.

But lately the opposition has singled him out for unprecedented and stinging personal criticism that's given the current crisis a sharper edge than previous confrontations.

On Sunday, security forces used tear gas and stun grenades to break up some 30,000 demonstrators. Scores were arrested. The authorities banned gatherings of more than 20 people.

Now the opposition is planning a mass public sit-in for this Sunday to protest the unusually harsh security crackdown.