President Gustavo Petro’s chief of staff and Colombia’s ambassador to Venezuela stepped down amid a widening probe into allegations of phone tapping and abuse of power, delivering another blow to an administration already reeling from legislative setbacks.

Petro announced Friday that Chief of Staff Laura Sarabia and ambassador Armando Benedetti will leave the government to ensure the credibility of the investigation, although he denied any involvement of his government in illegal interception of communications.

The case is undermining Petro just as he sends congress ambitious bills to overhaul the nation’s pension, health and labor markets. It also risks hurting his alliance of leftist parties ahead of regional elections in October.

The scandal erupted last weekend after a woman who had been employed by Sarabia as a nanny told local media that she had been interrogated and subjected to a polygraph test in a building opposite the presidential palace — an apparent abuse of power, since only the attorney general’s office is allowed to investigate crimes.

Sarabia had fired the woman, Marelbys Meza, and accused her of stealing thousands of dollars in cash from her apartment. To gain access to their communications, police improperly included Meza and a cleaner in an investigation into Colombia’s biggest drug cartel, to which they had no connection whatsoever, according to a statement from the Attorney General’s office, which started probing the case on Thursday.

Read more: Colombian Prosecutors Probe Officials Accused of Polygraph Abuse

Sarabia had said on Twitter the missing money amounted to less than $7,000, and that it corresponded to reimbursed expenses from foreign travel.

Meza had previously worked for Benedetti, who managed Petro’s presidential campaign. Local media reported that before the scandal erupted, Benedetti arranged for Meza to be flown to Caracas on a private flight, in circumstances that remain unclear.

Following her ousting Friday, Sarabia took again to Twitter saying she has the “peace of mind of having done things correctly and with integrity.”

The 2002-2010 presidency of Alvaro Uribe was also hit by wiretapping scandals.

A poll published Friday showed Petro’s approval rating plunged to 34%, from 50% in November.

(Adds officials leaving Petro government startig in third paragraph.)