When you join a party, you are wedded to the principle. It is another matter that no party has got any principles these days. For example, when you join BSP or SP, you must udnerstand fully that whatever Mayawati or Mulayam Singh says and does are the principles of that party and you should be ready to obey her/his orders. If you feel the party is deviating from its known stand, you may protest in the party forum and submit your resignation as member of that party and also your seat as MLA/or MP and seek re-election under your new party's symbol or as independent as the case may be.