Businessman Josué Gomes said in a written statement on Friday that he had been informed that a bloc of five centrist parties put his name forward as part of a decision to support Alckmin in October's election.

Former Sao Paulo governor Alckmin and his Brazilian Social Democratic Party (PSDB) have backed President Michel Temer's economic agenda, and signs that his campaign was gathering pace cheered investors hoping that Brazil will stay the course on Temer's unpopular but market-friendly reforms.

Brazil's currency, the real, rose 1.8 percent and the benchmark Bovespa stock index gained 1.4 percent on Friday, as traders cited better odds for Alckmin.

Speaking to reporters in Sao Paulo, Alckmin said talks were still under way as parties had to consult their rank and file.

"It's a done deal, as long as we do our homework," said the leader of one of the parties, who requested anonymity because the coalition's formal announcement was scheduled for next week.

Alckmin's new alliance comes at a crucial moment, as party conventions kick off and Brazilians tune in more closely to a presidential vote that is less than three months away.

A four-term governor of Sao Paulo, Brazil's largest state, Alckmin's cautious oratory and establishment credentials have inspired little enthusiasm so far from an electorate still stewing over a deep recession and huge corruption scandals.

The centrist bloc made up of the Progressive Party (PP), Democrats (DEM), Solidarity (SD), Brazilian Republican Party (PRB) and the Party of the Republic (PR) said in a statement late on Thursday that they would stick together and find the best ticket for Brazil, but did not mention Alckmin.

Sharing the ticket with Gomes, the son of a former vice president and chief executive of Companhia de Tecidos Norte de Minas, the biggest textile group in Latin America, would reinforce Alckmin's appeal in populous southeast Brazil.

The support for Alckmin dealt a blow to populist rival Ciro Gomes, a former governor of Ceará state not related to the textile executive, who had tempered some of his leftist rhetoric as he wooed the centrist coalition.

FOURTH IN POLLS

Alckmin is running fourth in current polling with just 6 percent of voter support, behind the former governor Gomes, environmentalist Marina Silva, and front-runner Jair Bolsonaro, a far-right nationalist who has capitalized on voter anger with political corruption and leads with 17 percent.

The centrist bloc brings with it valuable public funding for the Alckmin campaign and more than four minutes a day of free TV and radio time under electoral rules - an advantage over rivals in the highly fragmented field.

As Gomes on Friday accepted the presidential nomination of the center-left Democratic Labor Party (PDT) at a convention, he called for nationalist industrial policies to bolster Brazil's production of fertilizers, defense products and equipment for the oil and gas industries.

Gomes has warned that he would undo a proposed tie-up between Boeing Co and Brazilian planemaker Embraer SA and reverse the result of auctions giving oil majors access to enormous offshore oil reserves if elected.

Bolsonaro, a former army captain and apologist for Brazil's 1970-1980s military dictatorship, has not been able to forge alliances with other parties, who view him as too controversial.

His lack of allies will seriously handicap Bolsonaro when campaigning begins on Aug. 16, since his small party will have little money or free TV and radio time, allotted according to the number of seats parties have in Congress.

Unable to draw any other party to his ticket, Bolsonaro will pick Janaina Paschoal, a lawyer from his own party, as his running mate at a convention in Rio de Janeiro on Sunday, a source close to the candidate said.