A key member of Brazil's Congressional budget committee has recommended the approval of the 2014 accounts of President Dilma Rousseff's government, which could undermine her opponents' case for impeaching her.

Senator Acir Gurgacz, who is charged with reporting to the committee on a ruling by Brazil's Federal Audit Court that the Rousseff administration broke the law by disguising spending last year, said he recommends approving the 2014 accounts.

Rousseff's opponents are seeking to impeach her alleging that she broke Brazil's budget law by resorting to accounting tricks to hide greater public spending aimed at boosting the economy during her re-election campaign last year.

Rousseff's governing coalition has a majority of the seats on the committee, which is expected to follow Gurgacz's lead.

Should the committee vote in favour of his view and approve the 2014 government accounts, the impeachment process begun 2 December in the lower house of Congress will lose its grounds for seeking Rousseff's removal.

The unpopular Rousseff is fighting for political survival in the midst of a severe recession, and a massive bribery and kickbacks scandal that has implicated dozens of her allies. The president is not being investigated for corruption and insists that her opponents have no legal basis to impeach her.

"My public life has no stains at all," she said in a speech on Tuesday, repeating that an impeachment without grounds was tantamount to a coup d'etat against democratic rule.

Rousseff has said previous presidents have also used the same accounting tricks found by the TCU audit court, which reports to Congress on public spending. The court said she delayed payments owed to public banks that funded her government's social programs.

The TCU prosecutor who led the so-called "back peddling" investigation of Rousseff, Julio Marcelo de Oliveira, said it was up to Congress to rule on the case.

"We thought Congress would of course reject the accounts given the sheer volume of irregularities in 2014. But this is a political decision," he told Reuters.

The committee will vote on the case in early March following the congressional summer recess, a committee spokeswoman said.

Rousseff's chances of blocking impeachment improved last week with Supreme Court rulings on the proceedings that expanded the authority of the Senate, where she has a more solid backing, and reduced the clout of lower house speaker Eduardo Cunha, her arch enemy who triggered the bid to impeach her.