It is the greatest injustice anyone could do to another person, according to Brazilian President Dilma Rousseff, on the brink of impeachment.

"They want to condemn an innocent woman," she said, after losing a congressional vote over of her removal from office. "And save the corrupt."

Though Rousseff faces a 180-day suspension if the Senate follows Congress and votes to open a trial on Wednesday, she remains innocent until proven guilty. But the same cannot be said for many of those who campaigned against her - and who stand to form Brazil's next government if the president is sidelined.

In what could turn out to be Rousseff's final week as the country's leader, a cloud of corruption has cast a shadow over the line of succession and threatens to eclipse attempts to re-establish stability in Brazil. The storm brewed yet stronger this week after a last-ditch attempt to annul the congressional vote and call the process back from the Senate brought chaos to Brasilia.

Waldir Maranhao, who became interim speaker last week after the incumbent Eduardo Cunha had his mandate suspended, made the surprise move and threw the process into disarray.

Maranhao, of the Progressive party, had said that he wanted to "save democracy" and correct failings that would be "irremediable" in the future by annulling the April 17 vote.

But the decision by the substitute president of Congress, who is himself under investigation by prosecutors carrying out the massive "Car Wash" probe, was deemed "unconstitutional" and "absurd." Maranhao subsequently backtracked, saying he had "reversed the decision" to seek to stop the impeachment.

House speaker and impeachment author sent packing

All this followed a turbulent week in which Cunha - the lawmaker responsible for opening the impeachment process, and next in line for the presidency after Rousseff and her vice president - lost his position as speaker of the lower house.

Cunha, of the Brazilian Democratic Movement Party (PMDB), was deemed unfit to remain in the line of succession given he is also under investigation as part of the Car Wash operation into widespread bribery at oil giant Petrobras.

Teori Zavascki, Supreme Court justice, said Cunha "did not qualify" for the position while he faces allegations of accepting $5 million (4.4 million euros at the current exchange) in bribes and holding bank accounts abroad. Cunha was also convicted of and fined for vote-buying in the 2006 campaign but the court only reached this decision in 2012, when his then mandate was already over. He escaped censure.

Rousseff's reaction to his removal was "better late than never" but said the impeachment was "such a violent process that it required a person devoid of moral and ethical principles, accused of money laundering and offshore accounts to perpetrate the blow."

Deputy can become president, despite ineligibility to run for office anew

Meanwhile, as Vice President Michel Temer was assembling his cabinet to replace Rousseff this week, it emerged that he was ineligible to run for office for eight years under the country's "Clean Slate" election laws.

Temer, also of the PMDB, was convicted over illegal donations in 2014 at the electoral court in Sao Paulo. Under Brazil's law, those impeached or convicted by a panel of judges are temporarily barred from running for office.

However, the conviction would not stop him from taking over the presidency if Rousseff were ousted. In that case, he would become Brazil's first president without a clean record.

"He will start off in government with a problem of credibility and he will have to fight for the legitimacy of his position," said Juliano Griebeler, political analyst with Barral M Jorge consultancy in Brasilia. "He will be able to have a majority in the government, something which is really important for the president and which Rousseff could not do. But Temer cannot guarantee that this stability will continue in the medium or long term, especially as we get closer to the presidential elections of 2018."

Analysts suggested Cunha's departure from Congress was in Temer's favor as it removed one of the more controversial, powerful and divisive players from the game.

Convictions and allegations permeate Congress

But the interim speaker's attempts to derail impeachment have been seen as favorable to the government as the process drags on.

There are simultaneous moves to oust the speaker of Congress and the vice president as charges and allegations continue to muddy the names of those in positions of power. For instance, senior congressman Beto Mansur is next in line for Cunha's post, after interim speaker Maranhao. Mansur has 47 judicial indictments to his name including convictions for slave-like conditions on his soy bean farm.

Of all those in the line of succession to be speaker of the lower house, only two have clean records.

And of the 513 members of Congress, some 300 have had brushes with the law; 15 percent of them have been convicted. In the Senate, 60 per cent have a tainted record with several high profile members falling under the suspicion of the Lava Jato scandal including Renan Calheiros, president of house.

"The ideal would be to not name any politician who had his name cited by Lava Jato but if Temer does this, he will have almost no one from his party to nominate so he will contend that they are innocent until they are formally accused by a judge," Griebeler added.

Senator Romero Juca (PMDB), who was instrumental in his party's exit from the governing coalition and stands to take a key position under Temer, has four Supreme Court inquiries hanging over him, including the Lava Jato case.

Juliana Sakai, coordinator for Transparencia Brasil, which publishes data on the judicial records of politicians, said the public needed greater information on candidates for political office.

"There's always a lot of focus on the contest for president, for governor, for mayor," she said. "But the debate in relation to the legislature is very difficult, people don't know who to vote for, there are lots of candidates, lots of parties and little information about these people. For the voter, it's very difficult to follow this."

Sakai said politicians were able to benefit from Brazil's slow justice system, as well as a culture of nepotism.