* Shwe Mann's support could help Suu Kyi form government
* Myanmar's historic election takes place on Sunday
* Opposition party predicted to win most votes (Updates with Suu Kyi's reaction, clarifies rare interview in para 4)
By Hnin Yadana Zaw and Antoni Slodkowski
PHYU, Myanmar, Nov 5 (Reuters) - One of Myanmar's most powerful politicians, ousted as leader of the ruling party in August, said Aung San Suu Kyi's opposition party was the most popular in the country and he would work with the Nobel laureate in parliament after an historic election.
Shwe Mann leads a sizeable parliamentary faction of the ruling Union Solidarity and Development Party (USDP). If Suu Kyi fails to win a majority, support from one of the former top generals in the junta could help her form a government.
Shwe Mann has said little in public about his close ties to Suu Kyi, which aroused the suspicion of some USDP members and contributed to his dramatic sacking, the biggest shake up of Myanmar's political establishment since the end of military rule in 2011.
The two have met frequently and found much common ground, Shwe Mann told Reuters late on Wednesday in a rare interview with international media.
He and his allies were purged from the leadership by President Thein Sein.
Suu Kyi's National League for Democracy (NLD) is expected to dominate the election.
"The NLD has got the strongest support from the people," Shwe Mann said at his home after a day spent campaigning in the run-down township of Phyu, where he grew up.
While he hoped his party would win, he said the interests of the nation were more important than personal or party affiliations, and that cross-party cooperation was vital to Myanmar's future.
More than 30 million people will vote on Sunday in what has been billed as Myanmar's first free and fair election, a poll which will determine the scope of its democratic transition.
"Whenever Aung San Suu Kyi and I meet, we always talk about working together for the stability and development of the country," said Shwe Mann, who wore a blue checked shirt and traditional green "longyi" wrap.
"This cooperation will continue in the next parliament. We will work together for the country."
He did not detail how he would work with Suu Kyi, and said he would also be prepared to cooperate with other parties.
In a campaign speech in his constituency in central Myanmar on Wednesday, the 68-year-old referred to Suu Kyi as a role model.
Asked about her relationship with Shwe Mann and how they might cooperate at a news conference on Thursday, Suu Kyi said it would only be possible to evaluate the benefits of collaboration after the votes are counted.
In the immediate aftermath of Shwe Mann's removal in August, when asked if his sacking had cost her an ally, Suu Kyi said that "it is now clear who is the enemy and who is the ally," adding that her party would "work with the ally."
STRAIN WITHIN PARTY
Shwe Mann's remarks may put further strain on his relationship with the ruling party. He remains a member of the USDP and the speaker of parliament and declined to comment on his estrangement from party leadership.
The USDP on Wednesday denied reports it had expelled him, and Shwe Mann told Reuters he was still a member.
Shwe Mann's ties with Suu Kyi had led to speculation he could be a presidential contender if her party dominates the new parliament.
She is banned from the presidency under a constitution drafted by the military before it handed over power in 2011. The armed forces hold a veto over any charter changes.
Before his sacking Shwe Mann had been open about his presidential ambitions. In the interview, he stopped short of a full-blown declaration, but said he was willing to take on the job if elected.
"If members of parliament ask me, I'm ready to take any responsibility," said Shwe Mann, in response to a question about his presidential plans. "If they think I should be the president, I will be."
Thein Sein had many successes as president, but left much unfinished work, Shwe Mann said, while also laying out his own presidential vision.
"Whoever becomes the next president should continue the peace process," he said, referring to talks with several armed rebel groups, some of which signed a ceasefire in October.
"There should also be a leader who will solve the people's daily ... problems, who should work for the rule of law in the country. The president should be the one who people can trust."
Shwe Mann is an ex-general awarded the honorary title "Thura" for his achievements on the battlefield. He was widely seen as the junta's number three, before the military handed power to Thein Sein's semi-civilian government in 2011.
He antagonized the military by backing Suu Kyi's campaign to reform the constitution to limit the sway of the generals over Myanmar's politics.
About 60 percent of current lawmakers support Shwe Mann, he said, but would not speculate about his potential firepower in the new chamber.
The number of USDP politicians in parliament is expected to fall sharply, but even a small group could prove useful if Suu Kyi fails to muster the number needed to nominate a presidential candidate.
(Additional reporting by Simon Webb; Editing by Mike Collett-White and Raju Gopalakrishnan)
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