* Presidential spokesman denies rumors that Mantega to leave
* Speculation resurfaced after newspaper opinion piece
* Wave of protests fueled speculation of cabinet reshuffle
BRASILIA, June 25 (Reuters) - Brazilian President Dilma Rousseff is standing by her finance minister, Guido Mantega, presidential spokesman Thomas Traumann told Reuters on Tuesday, despite growing speculation that Mantega is on the way out following massive protests against government policies.
"Mantega has the trust of President Rousseff and will stay in charge of the Finance Ministry," Traumann said.
An opinion piece in newspaper Valor Economico on Tuesday added to market rumors that Mantega will leave, saying that he could be replaced by central bank chief Alexandre Tombini. The article also said the government has sounded out former central bank chief Henrique Meirelles about taking over from Mantega, who has been on the job for more than seven years.
The sudden wave of national discontent over high prices, bad public services and corruption that erupted in the streets of Brazilian cities two weeks ago took the popular Rousseff by surprise and led her to consider political reforms.
They were biggest demonstrations in more than two decades.
On Monday, Rousseff made a surprising proposal for a referendum on amending Brazil's constitution to reform political institutions that have lost credibility among Brazilians. .