A nationalist lawmaker has made clear his coalition, the Patriotic Front, will withdraw its support for the government unless Parliament overturns the President's veto on changes to Bulgaria's Electoral Code.

Krasimir Karakachanov, who co-chairs the Front, has meanwhile told NOVA TV broadcaster President Rosen Plevneliev's decision to return the amendments to Parliament for consideration was a "populist move" and succumbed to "a campaign [organized] by 5-6 people who raised hell explaining how they represented Bulgarians abroad but did not represent anyone but themselves."

Lawmakers are to vote on Wednesday on the veto which Plevneliev defended by saying the new legislation infringed on the constitution by making it difficult for some Bulgarian expats to vote.

The PF had proposed curbs to the number of polling stations opened abroad, arguing the move would restrict uncontrolled vote from Turkey.

MPs passed the change, but that sparked outrage from Bulgarians living abroad.

On Tuesday, representatives of parties either forming or backing the minority government met to seek common ground for the vote, with the deputy chair of Bulgaria's biggest party GERB hinting the veto might be overturned.

Hours earlier, a Parliament Committee recommended that lawmakers should support Plevneliev's move.