The fragile Pheu Thai government faces another threat to its rule, after the Constitutional Court agreed last Wednesday to consider a petition to dismiss Prime Minister Yingluck Shinawatra.

Filed by 28 opposition senators, led by the unelected senator Paiboon Nititawan, the petition is based on Yingluck’s 2011 decision to remove Thawil Pliensri as National Security Council (NSC) secretary-general.

The court’s decision to accept the petition is the latest move in a campaign to install an unelected military-backed regime. It follows a flagrantly anti-democratic decision to annul the February 2 election on the pretext that candidate registration did not take place in 28 constituencies where it was disrupted by anti-government protests.

The government called the election in an effort to shore up its rule after the opposition Democrat Party resigned from parliament in December to join protests by the People’s Democratic Reform Committee (PDRC), which calls for the government to be replaced by an unelected “people’s council.”

The Democrats and PDRC represent sections of the traditional ruling elite—namely, the military, the monarchy and state apparatus—which supported the 2006 coup that toppled Yingluck’s billionaire brother Thaksin Shinawatra. The PDRC’s predecessor, the People’s Alliance for Democracy, prepared that coup by staging protests that exploited popular hostility to Thaksin’s privatisation of state-owned companies and his brutal policies, including the police murder of around 3,000 people in a “war on drugs.”

The Bangkok-based elites are hostile to the Shinawatras’ limited social reforms, including cheap healthcare and subsidies for rice farmers, which have won the Pheu Thai Party a base of support among the country’s rural poor. The PDRC’s “people’s council” would dismantle these reforms and initiate measures aimed at further imposing the burden of the country’s economic crisis on the working class.

When a pro-Thaksin government was elected in 2007, the Constitutional Court dissolved it the following year on trumped-up charges of electoral fraud—an operation it is now attempting to repeat.

The court has given Yingluck 15 days to defend her decision to transfer Thawil to a role as prime ministerial advisor. Her cabinet has already reinstated Thawil as NSC chief, after being ordered to do so by the Supreme Administrative Court on March 7.

Thawil was secretary-general of the NSC and the now-defunct Centre for the Resolution of Emergency Situation (CRES) under the previous military-backed Democrat government. CRES organised the military crackdown in 2010 on pro-Thaksin Red Shirt protests in Bangkok, killing 90 people and injuring 2,000.

Other efforts are underway to remove the government by pseudo-legal means. The National Anti-Corruption Commission (NACC), which supports the opposition, has charged Yingluck with “neglecting her duty” by allowing financial losses and corruption linked to the rice subsidy scheme. If found guilty, she could be impeached.

The NACC is also investigating 308 pro-government senators and MPs after the Constitutional Court ruled that they violated the constitution by trying to pass legislation to make the senate a fully-elected body.

For now, the government remains in caretaker mode, with limited powers to enact laws and raise funds. The Election Commission, which also backs the opposition, declared on Tuesday that it could take five months to organise a fresh election.

Hundreds of thousands of so-called Red Shirts, drawn from the rural and urban poor, today began a three-day rally in the western Bangkok district of Thawi Watthana, organised by the pro-government United Front for Democracy Against Dictatorship (UDD).

It is the first major rally organised in Bangkok by the UDD, which confined its previous protests to Pheu Thai’s provincial strongholds. Since November, the PDRC has repeatedly stormed government buildings, blockaded major intersections and disrupted elections, while the UDD and Pheu Thai leaders urged their supporters to avoid a “confrontation” with the PDRC.

The “Red Shirt” protest this weekend has been called far from the PDRC rally site at Lumpini Park. Its purpose is to let off steam, and attempt to retain control over the Red Shirts. Yesterday’s Bangkok Post reported that a “key Pheu Thai Party figure in Isan... conceded that support from people in the North and Northeast may be waning.” The unnamed politician also noted that Pheu Thai MPs “have been reluctant to chip in financial support for the rally.”

The government and UDD are just as afraid of any movement of the Red Shirts as the opposition. In 2010, Red Shirt protesters in Bangkok raised demands for an end to poverty and inequality, going well beyond the UDD’s call for fresh elections. Despite their mutual animosity, Pheu Thai and the Democrats agree that austerity measures must be implemented and subsidies scrapped to appease big business.

A military coup cannot be ruled out. The anti-government channel ASTV accused Army Chief General Prayuth Chan-ocha of siding with the government, after he rejected PDRC leader Suthep Thaugsuban’s calls for the army to support the PDRC. In fact, Prayuth has repeatedly stated that the military will intervene in the event of violence between the opposing sides.

The PDRC’s protests have also been repeatedly attacked by grenades and unidentified gunmen. Both sides blame each other for the attacks, which have killed 24 people, but the PDRC clearly has more to gain by provoking military intervention.

Some 3,000 police officers and soldiers have been deployed to the Red Shirt protest. The army has set up checkpoints at the site and on roads leading into Bangkok. This is in addition to 176 checkpoints, manned by 5,500 soldiers, that have already been erected in the capital for several weeks. The army is also working closely with the PDRC’s hired security guards, who are manning some of the checkpoints.

Major General Apirat Kongsompong, newly-appointed commander of the 1st Division, King’s Guard, is directly in charge of the soldiers. Apirat played a key role in directing the 2010 bloodbath. A source told the Bangkok Post on March 8 that Army Chief Prayuth convinced Yingluck to approve his re-appointment as part of last month’s reshuffle of the armed forces.