Conservative MP Anne McIntosh, who voted against a string of equality measures, including same-sex marriage, has been de-selected by her local party association.
The MP lost a vote of confidence of activists in her Thirsk and Malton constituency in Yorkshire on Friday.
Ms McIntosh has been in a long-running dispute with local officials about her political future.
The MP, chair of the Environment Select Committee, has suggested she may stand as an independent.
Ms McIntosh, elected to Parliament in 1997, has been a stauch opponent of LGBT rights.
She criticised equal marriage in January last year. She said: “The government’s attention should now be focused on reviving the economy and fulfilling our commitment made at the last election of implementing the married couples’ tax allowance.
“My understanding of marriage is very clear. It is the union of a man and a woman, for their comfort, safety and sustenance, and for the upbringing of children. Civil partnerships ensure there is no discrimination, and in my view, marriage is special and should be respected and celebrated as such.”
She voted against the Equality Act in 2007 and against same-sex fertility rights the following year. She voted against the introduction of civil partnerships in 2004 and was absent in the vote on repealing Section 28.
Section 28 stated that a local authority “shall not intentionally promote homosexuality or publish material with the intention of promoting homosexuality” and that schools “could not promote of the acceptability of homosexuality as a pretended family relationship”.
It was introduced as part of the Local Government Act in 1988 by the Thatcher government.
Section 28 was later repealed under Tony Blair’s Labour government and the current Conservative Prime Minister, David Cameron, apologised for the policy in 2009.