BUENOS AIRES (Reuters) - Defeated Argentine presidential challenger Sergio Massa will give a tacit nod of support this week to rival Mauricio Macri, party sources said, giving an early boost to the opposition candidate's scramble for votes ahead of next month's run-off.
Macri delivered a humiliating blow in Sunday's vote to outgoing leftist leader Cristina Fernandez and her candidate, Daniel Scioli, who had been tipped by some opinion polls to win outright and now faces a nail-biting battle in the second round.
Massa failed to reach the run-off but his 5 million votes will leave him in an influential position over the next month.
Top officials in Massa's New Alternative alliance are compiling a manifesto with policy proposals.
"The document won't explicitly support Macri but it is a wink in his direction," said one close aide familiar with Massa's strategy.
A jubilant Macri wasted no time on Monday urging supporters of Massa and three other candidates knocked out in Sunday's ballot to fall behind him.
"We are here to represent you," Macri said. "Argentina needs a change and we are ready to make that happen."
Yet Massa is likely to shirk a public king-maker role because he will struggle persuading his supporters to follow him en masse and trying to do so could open rifts within his party.
Massa served as cabinet chief in Fernandez' first term before splitting with her. His own party is a dissident faction of the broad-based Peronist movement that dominates Argentine politics.
Many of his supporters believe Fernandez has mismanaged the economy but still find Macri's shock pro-market policies hard to stomach. Others balk at what they say would be four more years of brazen leftist populism under Scioli.
At play in the Nov. 22 presidential run-off is how Argentina deals with high inflation, a central bank depleted of liquid foreign reserves, an artificially strong peso currency and a debt default.
Another New Alternative alliance source said: "It will be easier for (Macri's) 'Let's Change' alliance to find common ground with the document than for the ruling party."
Former powerboat champion Scioli on Monday sought to draw a line under Sunday's election, which saw him win 36.9 percent of valid votes while Macri drew 34.3 support. Opinion polls had shown Scioli winning by a 10-point margin.
"Today starts a new election campaign that will decide the future of Argentina," a grim-looking Scioli told reporters.
For the second day running, Scioli went on the attack. Voters faced a choice between protecting industry, employment and social welfare and Macri's proposal "to liberalize the market and take on debt," Scioli said.
Macri's surprisingly strong showing on Sunday sparked a stunning rally in financial and equities markets.
Two of its main internationally traded bonds jumped to record or near-record highs while Argentine U.S. traded bank stocks soared, with Banco Macro and Grupo Financiero Galicia posted double-digit gains.
Macri is favored by investors for promising to free up the economy and conduct more investor-friendly policies. He is also the candidate seen as most likely to reach a deal with a group of "holdout" creditors whose lawsuit over bonds defaulted on by Argentina in 2002 caused a new and continuing default last year.
"If Macri wins ... we have a very interesting growth cycle ahead in Argentina," said Roberto Lampl, Head of Latin American Investments at Alquity Investment Management.
Even so, the road to growth would not be smooth because Argentina needs to devalue the currency and address a widening fiscal deficit, Lampl said.
Additional reporting by Buenos Aires newsroom, Karin Strohecker and Marc Jones in London, and Tariro Mzezewa in New York; Editing by Jonathan Oatis and Christian Plumb