Chokri Belaid, a Tunisian politician who has been a leading critic of the new government, was shot and killed outside his house on Wednesday, setting off a wave of protests from supporters and other opposition leaders. Belaid is the head of the Democratic Patriotic Party, which became the main opposition party after Tunisia elected it first post-revolution government in 2011. President Moncef Marzouki called the assassination "odious" during a speech to the European Parliament in France, before canceling a planned trip to Cairo and heading back to his country.

No one has yet to claim responsibility for the murder, but the crowds are likely to blame the Ennahda party, which leads the ruling coalition and holds the majority of seats in the assembly. Belaid had recently accused Ennahda and its Islamist allies of attacking a meeting of his supporters last weekend. Despite serving as ruling party in government and being a strongly religious party, Ennahda has promised in the past not to impose strict Muslim codes on the nation. But it has still faced harsh criticism from Belaid and others for not fixing Tunisia's economic problems and for not cracking down on the ultraconservative groups trying to enforce their strict Islamic beliefs.

More than 1,000 people have gathered outside the Interior Ministry, shouting "Shame, shame" and "The government should fall," prompting the leader of Ennahda to say that Belaid's killers are hoping for "a blood bath."

After Mohamed Bouazizi inspired the Arab Spring by setting himself on fire in the streets of Tunis in December 2010, Tusinia had seen one of the fastest and most peaceful transitions of any of the countries to overthrow its sitting ruler. However, slow progress on economic and political reforms and the influence of conservative Islamists on the new constitution has led to growing frustration and anger—anger that will only be ramped up in response to Belaid's murder.

Update 11:00 a.m.: Tunisia's opposition parties have announced they will suspend their membership in the constituent assembly and have called for a general strike on the day of Belaid's funeral, which will likely be tomorrow. The protests have only grown larger thoughout the day, leading police to respond with tear gas.