Caitlyn Jenner thinks she was "wrong" to back President Donald Trump in the 2016 election.

Caitlyn Jenner

Caitlyn Jenner

The 'I Am Cait' star - who was known as Bruce Jenner before her transition - had slammed the Commander-in-Chief for his treatment of the trans community and admitted she has been left "deeply, personally" hurt by his policies since coming to power as she believed he wanted to do good for her "vulnerable" peers.

She wrote in an op-ed piece for the Washington Post newspaper: "Trump was the first Republican presidential candidate to claim to support this valuable, vulnerable community, and I was encouraged by the applause he received when he said at the Republican National Convention in July 2016 that he would stand up for the LGBTQ community...

"Sadly, I was wrong. The reality is that the trans community is being relentlessly attacked by this president.

"The leader of our nation has shown no regard for an already marginalised and struggling community. He has ignored our humanity. He has insulted our dignity. He has made trans people into political pawns as he whips up animus against us in an attempt to energize the most right-wing segment of his party, claiming his anti-transgender policies are meant to 'protect the country.'

"This is politics at its worst. It is unacceptable, it is upsetting, and it has deeply, personally hurt me."

The 68-year-old former Olympian - who hit out at Trump earlier this week over a reported new policy to "narrowly define gender as a biological, immutable condition determined by genitalia at birth" - has vowed to learn from her "mistakes" and continue using her own position to "advocate and support" the trans community in the best ways possible.

She continued: "My hope in him -- in them -- was misplaced, and I cannot support anyone who is working against our community. I do not support Trump. I must learn from my mistakes and move forward.

"I am more determined than ever to find the best way to bring trans issues to the fore of our social and political conversation, domestically and abroad. I need to listen more to the members of the LGBTQ community and to learn more. I need to better use my voice, my privilege and my foundation to advocate and support our community.

"I must continue to educate political and corporate leaders about the issues of homelessness, job discrimination, violence, access to health care, prejudice in housing, depression, suicide and so many other issues that disproportionately affect our long-ignored community. I will still work with anyone who is committed to help our community.

"The world needs to hear us. The world needs to know us. We will not be erased."