FRANKFURT -- A lawmaker from German Chancellor Angela Merkel's party said on Monday he would quit parliament immediately after receiving payment for brokering face mask procurement deals for local authorities.

The scandal risks stirring more voter disgruntlement after Germany's ruling coalition of Merkel's conservative Christian Democrats (CDU) and the center-left Social Democrats (SPD) came under fire for a slow COVID-19 vaccination campaign.

Nikolas Loebel had faced criticism on Sunday after saying he would resign from the CDU faction but keep his seat in the Bundestag lower house until a national election in September.

"In order to avert further damage for my party, I withdraw from my Bundestag mandate," Loebel said in a statement on Monday. Over the weekend Loebel had said his conduct did not meet the "special moral duty" of his office.

His resignation comes one week before regional elections in the western states of Rhineland-Palatinate and Baden-Wuerttemberg, where Loebel's constituency is.

CDU-chairman Armin Laschet, a possible contender to succeed Merkel as chancellor, and other leading conservative lawmakers had urged Loebel to quit immediately as a member of parliament.

Facing similar allegations, another conservative member of parliament, Georg Nuesslein, on Monday quit the Christian Social Union (CSU), the CDU's Bavarian sister party, according to an announcement on the CSU Twitter feed.

Nuesslein's office didn't immediately respond to a request seeking comment outside of normal business hours. On Friday, he had quit as a deputy leader of Merkel's parliamentary group.

Nuesslein has denied allegations that he took more than 600,000 euros ($711,000) via a consultancy firm for mediating a mask purchase order by the state of Bavaria. He said on Sunday that he would complete his parliamentary mandate.

Prosecutors in Munich have said they are investigating initial allegations of bribery against Nuesslein.