A woman who suffered a gunshot wound to the head in the early hours of Sunday morning is understood to be an activist in the Black Lives Matter movement.
Police are appealing for information after finding the 27-year-old woman with life-threatening injuries in Southwark, south London, at about 3am.
In a statement on its Facebook page, the Taking The Initiative Party said Sasha Johnson had received numerous death threats.
The statement said: "It is with great sadness that we inform you that our own Sasha Johnson has sustained a gunshot wound to her head.
"Sasha has always been actively fighting for black people and the injustices that surround the black community, as well as being both a member of BLM and a member of Taking the Initiative Party’s executive leadership committee.
"Sasha is also a mother of three and a strong, powerful voice for our people and our community.
"Let’s all come together and pray for Sasha, pray for her recovery and show our support to her family and loved ones."
The Taking the Initiative Party is a political party that was registered with the Electoral Commission nearly four years ago and fielded its first candidates in May’s local elections.
Ms Johnson was reported to have cut ties with the Black Lives Matter movement in recent months.
Detectives from the Met’s Specialist Crime Command (Trident) are leading the investigation. No arrests have been made.
Detective Chief Inspector Jimi Tele said: "We are all hoping that this young woman’s condition improves.
"Our investigation is in its early stages and urgent inquiries are under way to establish the circumstances.
"I would appeal to the residents of Consort Road and the surrounding area to check any doorbell or dashcam footage for any suspicious activity that may relate to this investigation."
Anybody with information about the incident is asked to call police on 101 or tweet @MetCC quoting CAD 1172/23May.
They can also contact Crimestoppers anonymously on 0800 555 111
Last August, Ms Johnson was one of the organisers of the first-ever Million People March to protest against systemic racism in the UK. During the demonstration, hundreds of people took to the streets of west London.
She said she hoped the movement would "empower the community to strive for better".
"As a people, we’re not going to stop until we have equal rights and justice," she said.
"Our message is listen to us, hear our words, we want sustainable and tangible change.
"We don’t just want tokenistic promises, we don’t want it to come from a hegemonic standpoint. We want it to be for the people."
Ms Johnson, who got a first in social care at Oxford University, has "an immense passion for implementing change and justice and has been actively supporting the eradication of injustices in society by attending and leading protests", according to her page on the TTIP website.
"Although not everyone may agree with her methods, she is not afraid to stand up for what she believes in.
"She is also committed to feeding the homeless and has personally been involved in delivering food and groceries to families that are in need."
Black Lives Matter UK said on Twitter: "We are saddened to hear that Sasha Johnson is fighting for her life after a critical wound and following numerous death threats.
"While Sasha wasn’t part of our organisation, she impressively founded a new black-led political party and was dedicated to resist anti-black racism.
"Any attempt to intimidate or silence her, is an attack on all of us. Touch one, touch all.
"We pray that she will pull through this and those who threatened her life are held accountable.
"Our thoughts are with her children, family, and all impacted by this senseless attack."