Previously, Kuwaitis could cast ballots for four candidates. Critics of the change say it gives authorities a greater hand possibly to bribe voters or control candidates.
The presence of Western-oriented Kuwaitis in the protest group poses added challenges to the ruling system, which had generally counted on liberal support in the past. The emir had been lauded for standing firm against demands for stricter Muslim codes by hardliners, including calls to impose the death sentence on anyone convicted of insulting Islam.
Whether the broad-based opposition holds together remains one of the critical wild cards immediately after Saturday's election.
"The government and the opposition seem to be in a mood to escalate this further and neither side appears prepared to back down," said Kristian Coates-Ulrichsen, a research fellow who follows Gulf affairs at the London School of Economics. "Kuwait may be entering the most dangerous and volatile period in its history."
It got to this point through political brinksmanship and a series of gambits — with each one appearing to dig the country deeper into crisis.
In February, Islamists and their tribal allies won parliament elections and immediately pushed for greater clout in policymaking affairs, including more seats in the Cabinet.
After a few tense months, the Constitutional Court disbanded the parliament amid claims of flaws in the electoral district map, and reinstated the former government-friendly chamber from elections in 2009. That group of lawmakers, however, never managed to convene a session.
In September, the country's highest civilian court rejected the government's assertions about problems in the electoral map, forcing the emir to call new elections.
Kuwait also has been hit by a wave of labor unrest and strikes earlier this year, including walkouts that grounded the state carrier, Kuwait Airways, and temporarily closed customs posts and left several hundred trucks stranded at the border.
Calls for better working conditions have grown louder in the wake of the Arab Spring uprisings. Kuwaitis are used to well-paid government jobs and cradle-to-grave benefits that increasingly have become a burden on state finances despite the huge oil wealth.