BRASILIA (Reuters) - The acting speaker of Brazil's lower house of Congress early on Tuesday revoked his decision to annul the chamber's impeachment vote against President Dilma Rousseff, keeping the process on track for her to be suspended from office this week.

Speaker Waldir Maranhao decision on Monday to annul the lower house's April vote threw Brazilian markets into disarray and threatened to drag out a painful political crisis with a constitutional standoff that could have ended up at the Supreme Court.

Brazil's currency, the real, strengthened 1 percent early on Tuesday after the speaker's reversal - a reflection of investor hopes that a more market-friendly government will soon take over from the leftist Rousseff.

Maranhao, in an official statement to the Senate, did not cite any reason for backtracking on his surprise announcement. On Monday, he cited "procedural flaws" in annulling the vote, which had overwhelmingly recommended the Senate try Rousseff for breaking budget laws.

Senate President Renan Calheiros said on Monday that Maranhao was "playing with democracy" and vowed the Senate would press ahead with a vote on Wednesday. The vote is expected to suspend Rousseff for up to six months pending a trial.

Ueslei Marcelino / Reuters The acting speaker of Brazil's lower house of Congress revoked his decision to annul the chamber's impeachment vote against President Dilma Rousseff.

The impeachment process comes as the country is mired in the worst recession in decades. Rousseff has steadfastly denied committing any crime and has vowed to fight impeachment by all means legally possible.

With chances of her ouster growing, anti-impeachment protesters blocked roads in small demonstrations in Sao Paulo and Brasilia early on Tuesday. Rousseff's Workers Party and labor unions called for a national strike with street demonstrations and road blockages.

If the Senate votes on Wednesday to place Rousseff on trial, Vice President Michel Temer would step in as interim president. He would remain in the post until elections in 2018 if she is found guilty and removed permanently.

Speaker Maranhao, a little known figure in Brazilian politics before taking over as house speaker only last week, risked being expelled from his center-right Progressive Party, which supports Rousseff's impeachment, deputies said.

Paulo Whitaker / Reuters A vote on Wednesday is expected to suspend Rousseff for up to six months pending a trial. Brazil is in its worst recession in decades.

The impeachment process is unfolding as investigators pursue a separate, longrunning probe into a vast kickback scheme at state-run oil company Petrobras. "Operation Carwash" has ensnared dozens of top politicians and jailed chief executives from Brazil's biggest construction firms for paying billions in bribes to lock up bloated building contracts.

The Senate was likely to strip a former government leader in the upper house, Delcidio do Amaral, of his title as senator in a vote later on Tuesday. Amaral struck a plea agreement with prosecutors investigating Petrobras scandal.

(Writing by Silvio Cascione; Editing by W Simon and Frances Kerry)