Bondars was elected to the Riga City Council in June, having laid aside his Saeima mandate in order to run for the post of Riga mayor.
He told LTV that he opposed many of the decisions made by the Regional Alliance faction in Saeima recently but that the Sudraba vote had been the last straw.
Bondars was also dissatisfied with the party's approach in the ongoing tax reform and the fact that Regional Alliance MPs did not sign a petition to ask Agriculture Minister Jānis Dūklavs (Greens and Farmers Union) to step down.
Dūklavs, who featured in covertly recorded conversations involving Latvia's cadre of influential oligarchs (as previously reported by LSM) has come under scrutiny for his possible covert ownership of land plots in the vicinity of Riga port that he was offering to sell to the oligarchs to help them enable their plans.
Bondars' resignation means he has formally left the party he helped found and means the party has now lost both of its best-known members with maverick MP Artuss Kaimins having already quit to form his own party. Bondars will however continue working as an independent opposition council member at Riga City Council, he confirmed in an interview with Latvian Radio.
Inguna Sudraba was elected to chair the parliamentary committee tasked to probe why the 'oligarch case' was dismissed before being brought to court and investigate public security risks that might be worked out from the conversations.
Sudraba, a long-time public servant who held the post of auditor general in the State Audit Office for close to a decade and then went on to form the Latvia From the Heart party, is herself briefly mentioned in the transcripts released by Ir weekly.
Viesturs Koziols, a business associate of so-called 'oligarch' and former statesman Ainārs Šlesers mentions Sudraba by saying, "It has been decided in Moscow that Sudraba must be Prime Minister."
Though the alarming claim made in secretly recorded conversations has not been verified, it is seen by Unity and National Alliance as making Sudraba, unfit to chair the committee.
And despite a long-running public feud with Šlesers during her time as State Auditor, she was also famously filmed having a meeting with him at a Riga restaurant some years ago.
The right-of-center National Alliance faction says it will try to remove her from the post at the next Saeima meeting.
"An official of independent Latvia cannot be chosen in Moscow. Even the mere possibility should mobilize the political environment so that what's said is carefully investigated. I have turned to the Security Police for it to be investigated. The parliamentary investigation committee should analyze this episode and give citizens confident answers," National Alliance co-chairman Raivis Dzintars told Latvian Radio on July 28.
The appointment of Sudraba and the composition of the rest of the commission has drawn widespread criticism on social media too.