Less than 18 months after taking office on a wave of populist support, Haitian President Michel Martelly is now facing protests in a country still trying to rebound from the massive 2010 earthquake.

For three weeks, protesters have marched regularly in Haiti's biggest towns, furious over what they see as the government's inaction in the face of the rising cost of living in what is already one of the world's poorest nations.

The demonstrators also denounce politicians for lavish spending on luxury cars and official travel which they say brings no practical gain to the Caribbean country.

The grassroots movement was quickly joined by political groups hostile to Martelly's administration, which they accuse of trying to "install a dynastic and dictatorial regime."

At a meeting Wednesday in Cap-Haitien, Haiti's second largest city, opposition and civil society leaders were sharply critical, saying there is "increased vulnerability at nearly every level of society."

While the meeting was going on, thousands poured into the streets, demanding more government action to curb rising consumer prices and Martelly's resignation.

Law professor Frizto Canton said the government has a lot of work to do to regain the public's trust.

"The government should rethink its policy. There is an absence of forethought, planning and coordination in the state's decisions, which have led to these protests and calls for the president's departure," he said.

Even though Martelly's popularity has taken a hit, the international community has reminded disenchanted youth and other protesters that the president was elected for a five-year term, due to end in 2016.

The best bet for anyone who wants the president to leave "is to prepare a good candidate for the 2016 elections," said the UN secretary general's representative in the Caribbean nation, Chilean Mariano Fernandez.

Opposition groups see things differently, saying Haitians have the right to demand the early end of Martelly's mandate if he fails to play by the rules.

Constitutional historian George Michel said while he does not believe the protests will result in the president's ouster, Martelly is facing serious challenges.

"Martelly still has a certain popularity, but he has himself provoked some crises that will poison the rest of his term," Michel said.

Michel, a former journalist, accused the president of "wanting to control the electoral system, like all others before him."

In the protests, behind the slogans decrying difficult living conditions and corruption is another source of frustration: the upcoming local and partial legislative elections, under the watch of the controversial Permanent Electoral Council, considered by the opposition to be an arm of the ruling party.