Wisconsin's election board has agreed on Friday to conduct a statewide recount of votes cast in the presidential earlier this month.
The recount process, including an examination by hand of the nearly three million ballots cast in Wisconsin, is expected to begin late next week after Green Party candidate Jill Stein's campaign filed the paperwork, the Elections Commission said.
"The Commission is preparing to move forward with a statewide recount of votes for President of the United States, as requested," Commission Administrator Michael Haas said in a statement.
The recount must be finished by December 13.
In a Facebook message on Friday, Stein said she said she has raised at least $US5 million ($A6.7 million) since launching her drive on Wednesday for recounts in Wisconsin, Michigan and Pennsylvania - three battleground states where Republican Trump edged out Democratic nominee Hillary Clinton by relatively thin margins.
The chance of overturning the result of the election is considered very slim, even if all three states go along with the recount.
The Green Party candidate, who garnered little more than 1 per cent of the nationwide popular vote herself, said she was seeking to verify the integrity of the US voting system, not to undo Trump's victory.
"This was a hack-riddled election," she told CNN.
Experts urged extra scrutiny of the three states, Stein said, because they had "unexplained high numbers of undervotes," and "discrepancies between pre-election polling and the official result."
The filing deadline for a recount in Pennsylvania is Monday and in Michigan it is Wednesday.
Clinton would need to reverse the result in all three states for the overall election result to change.
Trump beat Clinton in Pennsylvania by 70,010 votes, in Michigan by 10,704 votes and in Wisconsin by 27,257 votes.
A representative for Trump's transition team on Thursday had no comment on Stein's effort, and Clinton has not commented either.
