By Renee Maltezou and Peter Graff

ATHENS (Reuters) - The charismatic Greek leftist who could determine the fate of the euro begins a tour of European capitals on Monday carrying a single message: it's time to talk.

In an interview on the eve of his first visit abroad since his surprise rise in a May 6 election, Alexis Tsipras veered occasionally into the combative rhetoric that has seduced disaffected Greek youth and alarmed Brussels and Berlin.

But he also stressed repeatedly that he wants negotiations to keep Greece in the euro. He said he was looking to forge ties with likeminded European figures, including new French President Francois Hollande, who want to soften austerity policies by finding new ways to encourage growth.

"The first reason we are taking this trip is because we want the governments of these important European Union countries, France and Germany, to see what we stand for: what is being transmitted in Europe about us is not what we represent and want," Tsipras told Reuters at the office of his SYRIZA party.

He will not be meeting government officials, but will see fellow leftists in France and Germany, including former French presidential candidate Jean-Luc Melenchon and Klaus Ernst and Gregor Gysi of Germany's The Left. He will hold news conferences in both capitals to get his message to a wider audience.

"We are not at all an anti-European force. We are fighting to save social cohesion in Europe. We are maybe the most pro-European force in Europe, because its dominant powers will lead the union into instability and the euro zone to collapse if they insist on austerity," he said.

While he repeated his assertion that the terms of a 130 billion bailout agreement Greece signed with international lenders in March are now a "dead letter", he said that if he comes to power he will seek a new policy mix to keep Greece in the euro.

"Yes, we do want Europe's support and funding, but we don't want the money of European taxpayers to be wasted. Two bailouts in a row went into the dustbin, into a bottomless barrel. If this continues we would need a third package in six months. Europeans and their leaders must realize this," he said.

"We want to make use of Europe's solidarity and funding to create the basis for our long-term reforms. But we need to know that in two-three years we'll have escaped this downward vortex, we will have growth, and we'll be able to pay back the money they gave us. There is no way we could pay them off if we continued this program."

CHE BEHIND GLASS

European leaders have reacted with open horror to the rise of Tsipras, a 37-year-old former Communist student leader, who in a May 6 election humiliated the socialist and conservative parties that ran Greece for generations and signed the bailout.

Tsipras placed second in the election, winning enough votes to deny the establishment parties a majority to form a government. Two days later he wrote a letter to European leaders declaring the bailout program "delegitimized".

In bitter coalition talks that followed, Tsipras refused to join the socialists and conservatives in a unity government, forcing President Karolos Papoulias to call a new vote in June.

Polls show Tsipras is now neck and neck with the conservative leader, and could well emerge with enough votes to become the next prime minister.

European leaders say that if the next Greek government spurns the bailout, they will have no choice but to cut off funding, which would effectively bankrupt Greece and force it out of the euro. The prospect sent the single currency tumbling last week and hurt the bonds of Spain and Italy, countries that could be next in the firing line if Greece collapses.

Tsipras's boyish good looks and forceful rhetoric have especially appealed to Greek youth, who have been hit the hardest by the economic crisis. Five years of recession have left more than half of young people jobless, and many blame middle aged political bosses for sacrificing their future to protect an older generation's perks.

The shopworn office of Tsipras's SYRIZA party, in a shabby old building in a slightly seedy neighborhood of central Athens, hardly looks like the headquarters of a group poised to be thrust into power.

Staff are young, in jeans and T-shirts, the men sporting varied patterns of facial hair. A faded poster of Che Guevera hangs on a wall behind a broken pane of glass.

Tsipras has been denied a meeting with new Socialist President Francois Hollande, who defeated conservative Nicolas Sarkozy on the same day as Greece's inconclusive vote, but Tsipras clearly sees Hollande as an ally in persuading Europe to abandon its austerity prescriptions.

Sarkozy's defeat had altered the political dynamics in Europe, depriving German Chancellor Angela Merkel of her main ally in promoting belt-tightening, Tsipras said.

"For the first time Merkel is extremely isolated," he said. "The implementation of the austerity policies - not only in Greece but also in Spain, in Portugal, Italy, Ireland and other places where fiscal consolidation plans based on austerity are implemented - obviously failed."

He pointed to the United States, where he said the Obama administration's stimulus program had helped make recession less severe than in Europe, and noted that Obama and Hollande appeared to see eye to eye at a meeting on Friday.

"At the Hollande-Obama meeting, the main issue was what happens with Greece," Tsipras said. "Until yesterday, what would happen to Greece was given: the people and workers would be crushed, labor rights would be demolished."

New negotiations for a Greek rescue should take place among elected leaders, rather than at the level of technical advisors from the EU, European Central Bank and International Monetary Fund, which he said was "degrading" for a Greek prime minister.

"For the first time after a very long time, we have the conditions and the terms so that this negotiation is in the interest of the people and against banks and capital."

Among measures he said he wanted to discuss would be funding from the ECB for state budgets - a proposal seen as anathema in Germany - and joint European bonds to fund a "Marshall plan" of investment in sectors like renewable energy.

"Greece is a blessed country. It has a lot of sun, it can manage its waters in a better way to produce energy, it has wind. It should become a renewable energy Eldorado," he said.

But such suggestions mean changing the European consensus on the need for austerity measures to reduce debt, as manifested by the cutbacks demanded in Greece's two huge bailout packages, which made its recession worse.

"If we prescribe a medicine that worsens the patient's health instead of curing the illness, the solution can't be to give him another dose, as we did with the second bailout.

"If the Europeans don't realize this we will have made a historic mistake, because the real patient is not only Greece.... We must realize that we must change the treatment before it is too late for Europe."

(Editing by Philippa Fletcher)