The widow of conservative activist Charlie Kirk has said the Turning Point USA organisation he founded will help elect JD Vance as president in 2028, despite the current US vice-president having yet to announce he is running.

Erika Kirk's endorsement on Thursday came on the opening day of Turning Point's annual America Fest conference, the organisation's largest gathering since her husband was shot dead in September.

"We are going to get my husband's friend, JD Vance, elected for 48 in the most resounding way possible," Kirk said, referring to the 48th president. Trump is the 47th.

Vance, meanwhile, is scheduled to speak at the event on Sunday.

Turning Point has been credited with helping Republican President Donald Trump expand his coalition of support, leading to his 2024 presidential election victory.