Having joined Sauber in 2022, Bottas is out of contract with at the Hinwil-based operation end of the season.
It will become the Audi factory team for 2026 and the German marque is already exercising influence over strategic decisions, including the signing of Nico Hulkenberg.
Bottas does not factor in that thinking, leaving the 10-time grand prix winner a free agent.
That had seen suggestions he could join Haas or Alpine, with Williams thought a long-shot given its links with Mercedes.
Mercedes junior, Kimi Antonelli, has been thought the front runner for the Williams drive alongside Alex Albon as a way of easing the teenager into F1.
However, multiple sources have claimed that Bottas will secure the seat, rejoining the team for which he drove from 2012 to 2016.
It was suggested the deal will be announced next month, around the Canadian Grand Prix.
When put to Williams, the team dismissed the suggestion as nothing more than the usual silly season speculation.
“There are always rumours in F1 and we aren’t paying any attention to them,” Speedcafe was advised.
“We have an exciting driver line-up and out focus is on the very tight midfield battle this year.
“We always have an eye on the future and are assessing our options for 2025 and beyond, but our focus is on delivering maximum success in 2024.”
Representatives from within the Bottas camp adopted a similar stance, noting that Williams is an option but that there are possibilities at Haas and Alpine, too.
Bottas returning to Williams has a number of implications, the highest profile arguably being that of Antonelli.
It’s known Williams requested a dispensation for the young Italian which, if nothing else, highlights the extreme interest in him.
However, nothing has been decided for his future despite the intense speculation swirling around the paddock.
At just 17, there’s also no need to rush a decision as his prodigious talent will not disappear on his 18th birthday.
The priority for Mercedes is developing him correctly rather than quickly.
For Bottas, the Williams drive fits his publicly stated criteria, which is firstly to remain in Formula 1 but also to be part of a project to drive a team forward.
“I wouldn’t get one year somewhere just to be in F1, just to hang on,” he said on Thursday in Imola.
“I need a long-term project with clear goals and with respect for what I can do and deliver.”
He added that he was 99 percent certain he will be on the grid next season – an strangely confident position to hold if he was in any way uncertain of his future.