The 2015 forecast is also cut from 4 per cent to 3 per cent.
It cited faster deceleration of economic activities and weak recovery, on the base-case scenario that the election would be held in the next 12 months or the second quarter of 2015 at the latest.
The unfavourable political condition would affect tourism and domestic demand and the V-shape economic recovery is unlikely.
In the best case which has the 10 per cent probability, the reform roadmap, constitutional amendments and referendum, as well as the election can be completed within 6 months.
In the worst case scenario which has the 40 per cent probability, the interim government can hold the election within 15 months amid widening political rift and slow recovery of the global economy.
It sees the Thai baht end the year at 36.14 per US dollar.