BRASILIA, May 11 (Reuters) - Henrique Meirelles, the man tipped to be Brazil's next finance minister, will draw on his stellar reputation as central bank governor between 2003 and 2010, when the economy boomed, to revive investors' confidence in Latin America's ailing giant.
But former colleagues and politician insiders warn that the long-time Wall Street banker's ambition to one day be president could raise tensions within a new governing coalition.
Meirelles unsuccessfully vied to be President Dilma Rousseff's vice-presidential running mate in 2010. Now the man who beat him, Michel Temer, is expected to entrust Meirelles with hauling the world's ninth largest economy out of its deepest recession in decades.
Temer will take the helm of an interim government on Thursday if, as expected, the Senate votes to put Rousseff on trial for breaking budget rules.
Investors believe Meirelles' close ties to the business and political world will help Temer turn things around after years of mismanagement by Rousseff.
But members of Temer's Brazilian Democratic Movement Party (PMDB) are concerned Meirelles' political ambitions could antagonize future cabinet peers ahead of the 2018 presidential election.
Temer's likely pick as foreign minister, Jose Serra, an influential senator who nurtures hopes for 2018 after two failed presidential runs, has demanded a bigger say in trade policy in the new government, putting him on a possible collision course with Meirelles.
"Meirelles is the perfect man for the job, but I'm afraid that his presidential ambitions could be harmful for the coalition," said an official close to the top brass of the Social Democracy Party (PSDB), Temer's main ally in Congress.
"They need a strong coalition to be able to get the economy going again."
The example of Fernando Henrique Cardoso, the long-time leader of the PSDB, lingers in the minds of many in Brasilia. Cardoso was catapulted to the presidency in 1995 after he quelled hyperinflation as finance minister in the government of Vice President Itamar Franco.
"Many of his potential rivals are concerned that Meirelles could turn out to be another Cardoso," said Paulo Kramer, a Brasilia-based political consultant. "But that will depend on whether he is able to fix the economy, which is not an easy task."
To regain investors' trust, Meirelles - the former chairman of now defunct BankBoston - will first have to stop the bleeding of fiscal accounts, which cost Brazil its coveted investment-grade rating last year.
Meirelles declined interview requests but sources close to the incoming government say he is preparing tough measures to limit public spending and reform an overly generous pension system once he is named minister, which could take place as soon as Thursday.
His success will hinge on the strength of political support from Temer's coalition, as austerity will anger Brazilians struggling with rising unemployment and debts.
"The honeymoon will be brief and they know they have to hit the ground running," said Edwin Gutierrez, who helps manage $10 billion in emerging market debt for Aberdeen Asset Management in London. "They need to be aggressive, but the big question is how much the PSDB and others are willing to play ball."
People who have worked with Meirelles said the soft-spoken banker is an avid negotiator who showed his mettle by resisting pressure to lower interest rates as central bank chief.
A civil engineer by training, Meirelles learned the monetary policy ropes by bringing some of the brightest economists to work with him at the central bank. Former colleagues say he is a tough boss who demands a lot from his subordinates, but knows how to delegate.
"His tough style can scare some people because he is someone who demands a lot and makes things happen," said Joao Antonio Fleury, who worked with Meirelles on the bank's board of governors between 2003 and 2007.
"Politics never influenced our interest rate decisions ... Meirelles was able to manage political pressure to allow the bank's staff to do its job."
Meirelles is drafting top market economists to be part of his team and wants Itau chief economist, Ilan Goldfajn, to be the next central bank chief, two Temer aides told Reuters.
Known for keeping his cool during a crisis, Meirelles is a private man who dislikes small talk, but is open to dissenting views when making decisions, former aides said.
"He has a big ego, which is the only point that has to be managed," said another person who worked closely with him. "This is a guy who is very goal driven and very ambitious politically and he knows that if he wants to get the presidency he will have to manage his ego."
Coming from a family of politicians in the soy-producing state of Goias, Meirelles was elected congressman in 2002.
Even with the blessing of then-President Luiz Inacio Lula da Silva, Meirelles lost the battle to be Rousseff's running mate in 2010 to Temer, a three-time speaker of the lower house who could count on the support of his PMDB party, the country's biggest.
In 2010, Meirelles, currently the chairman of the holding company that controls the world's biggest beef producer JBS SA , said he "never had political ambitions."
Still, many of his former government peers and subordinates say his dream is to one day become president.
Over the last 14 years, Meirelles has changed party three times. He was considered in 2014 as candidate for the governorship of Sao Paulo, the country's most populous state.
Reporting by Alonso Soto; Editing by Daniel Flynn and Kieran Murray