abolish all regional parties and allow only 3 national parties (ruling, opposition, neutral). all these people will have to join either of the three national parties much in advance of the election and contest. once lost or gained, they cannot withdraw or change over to another national party for a period of 5 years.
Likewise, in every state, there can only be 3 regional parties (ruling, opposition, neutral) to contest the state elections, affiliating to either of the 3 national parties.
Like this we can have a choice of voting pattern and stability in government.