Former Victorian Nationals leader Peter Ryan will quit state politics today, ending a 23-year run in the state’s parliament.

The decision will trigger a by-election in the seat of Gippsland South, which Mr Ryan has held since 1992.

• Nats leader quits following poll loss
• Who, us?: Vic election not our fault: federal minsters
• Labor rises to power: we won’t let you down 

Mr Ryan was Nationals leader for 15 years before stepping down from the role in December.

He was Deputy Premier in the Baillieu and Napthine Coalition governments and also served as Police Minister under Ted Baillieu.

He was also the Regional and Rural Development Minister in both governments.

The seat of Gippsland South covers the major townships of Sale, Leongatha and Korumburra.

It has been considered a very safe Nationals seat.

On December 4, 2014, Nationals MP Peter Walsh was elected as the Leader of The Nationals in Victoria.

Recently elected Steph Ryan, who holds the newly formed seat of Euroa, has been elected as Deputy Leader.

“I am honoured to follow in the footsteps of Peter Ryan, who set a leadership standard I aim to emulate,” Mr Walsh said.

“As leader, I am determined to show to the people of regional Victoria that it is The Nationals who have their best interest at heart. I firmly believe The Nationals are the only party that truly represents regional Victoria.”