By Hnin Yadana Zaw and Simon Webb
NAYPYITAW/YANGON (Reuters) - Myanmar President Thein Sein had tried and failed at least twice before to topple his arch-rival Shwe Mann, but when armed police burst into the headquarters of the country's ruling party late on Aug. 12 he finally succeeded.
Police piled the mobile phones and computers from those inside on a desk and then stood by as the president's supporters met to enact an order from the president to replace Shwe Mann as chairman of the Union Solidarity and Development Party (USDP).
By reasserting his grip on the party Thein Sein boosted his own prospects of retaining the presidency, while dampening optimism among those inside and outside the former Burma who hope for a quickening of reforms after an election in November.
"I heard people coming in and when I looked up from the computer I was surrounded by half a dozen armed guards," said one person who was inside the building when the police entered, declining to be identified due to concern for personal safety.
"They did not draw their weapons. It's obvious they didn't want anybody to communicate to the outside world."
Shwe Mann was not there, and the lockdown ensured neither he nor his allies could make any countermoves during the crucial hours in which the president's supporters were taking control of the party.
The manoeuvre, which had echoes of the purges of Myanmar's junta-ruled recent past, effectively took Shwe Mann out of the running for the presidency less than three months before the country's first free general election in years.
Advisers told Reuters that it also derailed a plan the deposed party chairman was poised to announce that may have included a speedier transition to full democracy.
Thein Sein, meanwhile, has cleared the way to either remain president himself or to impose a candidate of his choosing, if his party can form a majority coalition after the vote.
A former top-ranking general in a party dominated by retired military men, Shwe Mann was no radical reformist. But he had become a stronger voice for reform in the party and was working on a wide-ranging policy document that may have broadened the scope and pace of reforms, advisors said.
He drew the suspicion of the president's faction by building ties with their nemesis, Nobel laureate Aung San Suu Kyi.
"There was an internal crisis in the party," Information Minister and spokesman for the president Ye Htut told Reuters. "This kind of leadership change is not a good thing for the USDP or any other political party. They did it as a last resort."
Shwe Mann's office has declined requests from Reuters for an interview since his ousting.
ERA OF REFORM
Thein Sein ushered in the reforms since 2011 that have made resource-rich Myanmar a partial democracy after almost half a century of isolation and military rule, but many feel the reform process has stalled.
The sacking of Shwe Mann, who has made no secret of his ambition to become president, was another blow to international and domestic confidence in that process.
In interviews with members of the ruling party, advisers to the USDP and diplomats, Reuters has learned that the president had failed at least twice to unseat Shwe Mann from the position of party chairman through backstage machinations.
Shwe Mann and his allies blocked two previous attempts to oust him at leadership meetings - one in December and another in May - a party adviser and a Western diplomat told Reuters.
Both meetings ended in stalemate after the two factions jousted over who should be the presidential candidate and chairman, and the party's list of election candidates, the sources said.
"These attempts have been going on since last year," said Win Oo, a rank-and-file USDP lawmaker supportive of the ousted chairman, although he said he was unaware of the details.
Emboldened, Shwe Mann used his position as speaker of the lower house of parliament in an increasingly assertive push to become the country's leading presidential candidate.
He antagonized the military by backing Suu Kyi's campaign to change the constitution, which grants unelected members of the armed forces a quarter of the seats in parliament.
That was a red flag for hardliners, already facing the prospect of Suu Kyi's National League for Democracy winning the lion's share of contested seats in November's poll.
"The hardliners from the military and the president strongly disliked his effort to amend the constitution," said one USDP lawmaker, who was at party headquarters when the security forces locked it down, speaking on condition of anonymity.
"Shwe Mann had been trying to reform the USDP and the military ordered him to stop."
Divisions worsened after the death in July of ex-colonel and USDP disciplinarian Aung Thaung, who was seen as a restraining influence on the ambitious Shwe Mann.
Aung Thaung was an ally of Shwe Mann but retained a strong relationship with both the president and the military. With him gone, the knives came out.
Some members of the USDP executive committee sent Thein Sein a letter a few weeks ago voicing concerns about Shwe Mann's policies and the party's decision-making process, Ye Htut said.
Tensions rose further the day before Shwe Mann was sacked, when the USDP's parliamentary candidates list omitted the majority of a group of around 150 officers who retired from military service to run for parliament.
It is unclear what role the country's powerful military played in the downfall of Shwe Mann, but they must have acquiesced to the use of force, political observers say.
An order to deploy police would need approval by Home Affairs Minister Major General Ko Ko. The ministry is one of the three allotted to the armed forces under the military-drafted constitution.
"What they did was a demonstration of power," said USDP lawmaker Win Oo. "Showing to others, 'watch out, we can do this'."
(Additional reporting by Antoni Slodkowski in NAYPYITAW and Aung Hla Tun in YANGON; Editing by Raju Gopalakrishnan and Alex Richardson)