Greek Prime Minister Alexis Tsipras accepted the resignation of his foreign minister on Wednesday, Greece’s first major political casualty in a drive to end a decades-old name dispute with Macedonia, Reuters reported.

Tsipras has said he will do whatever is required to ensure an agreement reached in June to rename the neighboring country ‘Republic of North Macedonia’ gets implemented, but the deal faces opposition on both sides of the border.

Foreign Minister Nikos Kotzias, who helped negotiate the name deal, and Defence Minister Panos Kammenos clashed over the issue in cabinet on Tuesday. Kammenos, who heads a small right-wing party, views the deal as a national sellout.