Brazil's biggest party announced on Tuesday it is pulling its members from the governing coalition, dealing a major blow to embattled President Dilma Rousseff.
The Brazilian Democratic Movement Party (PMDB) decided at a leadership meeting that its six remaining ministers in Rousseff's cabinet, as well as all other party members with government appointments, must resign or face ethics proceedings.
READ MORE: Rousseff faces impeachment, coalition collapse
The break sharply raises the odds Rousseff will be impeached by Congress in a matter of months, or even weeks, which would put Vice President Michel Temer, leader of the PMDB, in the presidential seat.
Rousseff is embroiled in corruption allegations and accusations that she manipulated economic information - all of which she denies.
Al Jazeera's Gabriel Elizondo, reporting from the capital Brasilia, said the PMDB's decision was an "absolutely huge setback" for Rousseff.
"[PMDB] was her key ally party in her coalition, and with the entire party now saying they are breaking away from Rousseff’s ruling coalition, it basically signals that her coalition is crumbling," Elizondo said.
"This really sets into motion a whole new phase in this impeachment process with Dilma Rousseff now facing an even higher and harder uphill battle to try and save her presidency."
Rousseff is struggling to save her presidency amid the worst economic recession in a generation and the widening fraud investigation that started at state-run oil company Petroleo Brasileiro.
On Monday, the Brazilian Bar Association (OAB) filed a legal request to impeach the president for obstructing justice and fiscal accounting tricks.
READ MORE: Rallies in Brazil call for Rousseff's removal
Rousseff already faces an impeachment process over the alleged manipulation of government accounts that opposition parties maintain helped her win re-election narrowly in 2014 by allowing her to boost public spending.
The second request by the bar association, which represents one million lawyers, also involved Rousseff granting international football body FIFA tax-exempt status during the 2014 World Cup.
In reaction to the claims, Tourism Minister Henrique Eduardo Alves turned in a resignation letter on the same day, becoming the first prominent PMDB minister to step down from Rousseff's government.
Our correspondent said Tuesday's PMDB decision has now made it extremely difficult for Rousseff to gather the number of votes required - 171 - to block her impeachment.
"Right now, her people are huddled around literally counting votes," Elizondo said.
"Even before this party broke from her coalition, it was going to be a very tight impeachment battle and a very tight vote in Congress. Now, it's not with total certainty but pretty close that she is going to have a very difficult time trying to overcome this impeachment."
The president has repeatedly said she is not going to step down and has likened the moves to impeach her to a coup.
Source: Al Jazeera and agencies