The United Front for Democracy Against Dictatorship (UDD) begins a three-day rally Saturday that is billed as a show of strength in light of moves by independent agencies which threaten to strip Yingluck Shinawatra of her caretaker prime ministerial post.
But the rally will also pose a test of support for the red-shirt movement, as insiders concede the goal of drawing half a million supporters may be too ambitious.
A key Pheu Thai Party figure in Isan, who spoke on condition of anonymity, conceded that support from people in the North and Northeast may be waning as Pheu Thai Party MPs have been reluctant to chip in financial support for the rally.
The red shirts will gather on Utthayan Road, formerly known as Aksa Road, in Thawi Watthana district in western Bangkok, where they will camp for two to three days. The road serves as a link between Phutthamonthon Sai 3 and Phutthamonthon Sai 4 roads.
The source said the UDD wants to attract a huge turnout to oppose independent organisations and the Constitutional Court, which are considering dereliction of duty and charter violation cases against Ms Yingluck.
If indicted, she will be required to cease her official roles immediately.
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The UDD also wants to organise a show of strength against the anti-government People's Democratic Reform Committee (PDRC), which is pushing for a "neutral" prime minister to be installed.
However, the source said it appears the red-shirt movement in the North and the Northeast, which are the UDD's key support bases, is less active than it was in 2010 when it rallied in the capital to oppose the Abhisit Vejjajiva government.
The source said local people in the region now felt less emotionally involved with the UDD's core leaders than they did in the past.
This is partly because the people are aware the caretaker government has made mistakes and brought problems on itself, particularly cases relating to the rice-pledging scheme and the transfer of National Security Council chief Thawil Pliensri, the source said. Local people have become bored with politics, with low voter turnout at the Feb 2 general election and the Senate poll proof of this sentiment.
However, UDD chairman Jatuporn Prompan remained confident of the success of today's rally. He yesterday accused the charter court of trying to seize power from the legislative and executive branches as well as from the people.
"The UDD cannot afford to let this happen, and it therefore feels the need to rally for three days," Mr Jatuporn said.
The red-shirt supporters will go home to celebrate the Songkran festival, after which they will come back to stage more rallies, the UDD leader said.
The Myanmar embassy in Bangkok and NGOs working with migrant workers have issued warnings advising Myanmar nationals to avoid getting involved in the political conflict.
The warnings come as anti-government protesters stir up rumours that migrants will be enlisted to swell the UDD's ranks at today's rally.
Caretaker Labour Minister Chalerm Yubamrung rejected the rumours, labelling them baseless.
As chief of the Centre for Administration of Peace and Order (Capo), Mr Chalerm also said police and the military will ensure UDD and the PDRC supporters do not clash.
Security assessments suggest the situation is unlikely to spiral out of control and intelligence reports indicate there will be no clashes, Mr Chalerm said, adding that authorities will treat demonstrators from both camps equally.
The UDD and the PDRC are both staging rallies in Bangkok today. PDRC supporters will gather at their main rally site in Lumpini Park, a long way from the red shirts.
PDRC co-leader Thaworn Senneam said yesterday about 500 of the protest group's leaders from provincial branches will meet PDRC secretary-general Suthep Thaugsuban at Lumpini Park.
Mr Suthep will outline the group's next moves, Mr Thaworn said.
Capo worker Sirima Sunawin told a press conference yesterday that 19 companies of security personnel, comprising more than 3,000 police officers and soldiers, will be deployed around the UDD rally venue.
Security checkpoints will be set up to search vehicles and people for weapons, and police and soldiers will also jointly patrol areas around the rally site.
Army deputy spokesman Maj Winthai Suvaree said an operations centre had been set up to closely monitor the UDD-led rally.
He said Maj Gen Apirak Khongsompong, commander of the army's 1st Division, King's Guard, will be responsible for overseeing the overall military operation as well as coordinating with Capo.
Maj Gen Apirak said about 300 military personnel from his division have been deployed at two security checkpoints at the UDD rally site.
They have also been assigned to work with police officers at six other checkpoints around the rally site.
Even if the UDD protest area is not covered by the Internal Security Act, police and soldiers are still required to ensure security there, Maj Gen Apirat said.
Nisit Sinthuprai, a former Pheu Thai Party MP and a red-shirt leader in the Northeast, said yesterday more than 200,000 supporters from Isan will join the rally today.
The UDD rally is intended as a show of opposition to a potential coup and any efforts to topple the democratically elected government, as well as to the PDRC's move to appoint a neutral prime minister, Mr Nisit said.
Anuwat Tinraj, another UDD co-leader in the Northeast, said the rally is also intended to show that many people disagree with the PDRC and to show that they do not accept the authority of independent organisations.
Kwanchai Praipana, a red-shirt leader in Udon Thani, said more than 1,000 volunteer guards, known as the Volunteers for Protection of Democracy, from 20 northeastern provinces will be sent to ensure security at the rally today.
The guards just finished their training on Thursday, and today's rally will be their first security mission, Mr Kwanchai said.
Siriwat Jupamattha, a UDD coordinator in Phayao, said at least 50,000 red shirts in the North will make the trip to Bangkok for the demonstration.
A Pheu Thai source said senators-elect with links to Pheu Thai were each told to bring at least 500 people to the rally.