“Third front is a group of political parties which are not actually political allies but come together under a certain common agenda.”
Basically these are regional parties which have their base and support in a particular state. National parties have a national agenda because they have to represent the whole country whereas the regional parties, because of the question if their survival have to represent the issues of a particular state. Such regional parties come together under a certain leadership and agenda.
Are they necessary? Yes, because in parliament every issue of the country needs to be presented and discussed and since national parties have to deal mostly with the issues affecting the whole nation, sometimes issues affecting a little portion of whole of the population are left. And parliament is the ultimate step of democracy, every voice should be raised there. So yes they are necessary.
Is it realistic? I doubt that because sometimes the issues of the states and ego of the leader conflict. The question of the issues converts into clash of ambitions.
Few of the political parties and their leaders are:-
RLD – Lalu Yadav
JDU – Nitish Kumar
SP – Mulayam Singh Yadav
however right now there is nothing like third front in Indian politics but I think these parties need to be included:-
TMC – Mamta Banarjee
BJD – Naveen Patnayak
AIDMK – Karunanidhi
DMK – Jayalalita
BSP – Mayawati
and I’m not sure but in near future you may find AAP into the same list.