The correct answer is defection.

• Changing party allegiance from the party with which a person got elected to a different party is called defection.

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• Anti-Defection Law
  • The 52nd Amendment Act of 1985 provided for the disqualification of the Members of Parliament and the State Legislatures on the ground of defection from one Political Party to another.
  • Disqualification on ground of defection not to apply in case of a split.
  • A member of a House belonging to any political party becomes disqualified for being a member of the House,
    • If he voluntarily gives up his membership of such political party; or
    • If he votes or abstains from voting in such House contrary to any direction issued by his political party without obtaining prior permission of such party and such act has not been condoned by the party within 15 days.
  • An Independent member of a House becomes disqualified to remain a member of the House if he joins any political party after such election.
  • A Nominated member of a House becomes disqualified for being a member of the House if he joins any Political Party after the expiry of six months from the date, on which he takes his seat in the House.
  • Member of Parliament or a State Legislature can be disqualified for defying a whip only.

• Whip:
  • A directive issued by any political party to ensure the support of its members voting in favour or against a particular issue on the floor of the House.