What does Bangkok explosion mean for antigovernment protests?

Demonstrators have been attempting to 'shut down' Bangkok since Monday. Dozens were injured today as violence escalated after days of relative calm.

An explosion during an antigovernment march in Bangkok today wounded at least 36 and raised concerns about escalating violence after the protest movement appeared to be losing steam in recent days.

Police told Reuters that an explosive device was thrown at a crowd marching with protest leader Suthep Thaugsuban near Chulalongkorn University in downtown Bangkok.

So far, no one has taken responsibility for the blast; the government and the protest movement blamed each other for the attack, which was likely caused by a grenade, AFP reports.

A spokesman for the protest movement told Reuters that Mr. Suthep was about 100 feet away from the explosion and was unharmed.

Antigovernment demonstrators have been attempting to “shut down” Bangkok since Monday by blocking major intersections and staging rallies throughout the city. They have vowed to occupy the city until Prime Minister Yingluck Shinawatra resigns and they have rejected her call for an election on Feb. 2.

So far, Prime Minister Yingluck’s government has “been praised for a restrained response to a political crisis that has been percolating for several months,” as The Christian Science Monitor’s Bangkok correspondent reported yesterday:

Police have put up no resistance to protesters blockading major intersections in Bangkok and government ministries have quietly relocated to temporary offices in response to threatened occupations.  

At least eight people have been killed and hundreds injured since the latest unrest broke out. However, none of the incidents have directly involved Thailand's influential and coup-prone army, which has called for restraint from both sides.

But the Monitor’s correspondent also noted that progovernment supporters in Bangkok are ready to act if their leaders ask them to protest and that some hardcore supporters have stockpiled ammunition and weapons.

The Council on Foreign Relation’s Joshua Kurlantzick warned earlier this week that “Many currents of tension run just below the surface of the situation in Bangkok, and were visible even on the peaceful first day of protests.”

Risk analysis firm Maplecroft and the International Crisis Group have issued warnings this week that the window of opportunity for a peaceful solution to Thailand’s conflict is narrowing.

On the other hand, Chulalongkorn University professor Pasuk Phongpaichit and historian Chris Baker write in The New York Times today that, despite today’s blast, the protesters are “losing ground with a constituency whose support they badly need: the urban middle class," and that could open up the path toward a solution:

...the demonstrations have threatened to become so disruptive to everyday life and the economy that even people who support the opposition are being turned off it. This is a significant shift, for it presents Thailand with an 11th-hour opportunity to find a peaceful resolution to the deadlock. 

The protests are the latest iteration of a cycle of violence between Bangkok’s middle class and traditional elite, and the largely poor and rural supporters of Yingluck and her brother Thaksin Shinawatra, the self-exiled former premier who was removed in a military coup in 2006.  

Yingluck has called for early elections on Feb. 2, but the opposition vows to boycott the polls – expected to be easily won by Yingluck – in favor of establishing an unelected people’s council.

Protests were sparked in early October when Yingluck’s government attempted to pass an amnesty bill that would have brought her brother back to Thailand.