St Julian's mayor Albert Buttigieg has announced he will run in a casual election, in a move that ends speculation the PN's deputy leader could be co-opted to parliament.

The 10th district seat was vacated following the death of Robert Arrigo last week and will be filled by a Nationalist Party MP under election rules.

After contesting in March, three PN candidates are eligible to participate in the casual election. They are Buttigieg, former MP Karl Gouder and newcomer Emma Portelli Bonnici.

In a Facebook post on Monday, Buttigieg became the first to submit his nomination. He said he had done so "with respect to the democratic process and the citizens in the 10th district". 

Buttigieg was the last candidate to be eliminated from the race for a 10th district seat, though this is no guarantee that he will win a casual election. 

He is the first candidate to confirm he will run in the election to be held on October 28.

There had been speculation in PN circles that none of the candidates would apply, making co-option necessary.

This would have potentially allowed Alex Perici Calascione, the party's deputy leader, to be nominated to parliament. 

Last week, party leader Bernard Grech began to hold meetings with the three candidates in the running for the seat.

The PN would not confirm speculation that it was considering co-opting Perici Calascione, saying only the party would "consider all options". 

Buttigieg had clashed with the PN after the March election. He claimed that before the election a party official had promised a construction "fat cat" that they would shut him up. 

Buttigieg has been a vocal campaigner against over-development in St Julian's.

Portelli Bonnici, who has yet to say whether she will stand, also clashed with the party, saying it had ignored her after she failed to get elected.