Supporters of US President-elect Donald Trump have moved the courts to prevent or halt election recounts in Michigan, Pennsylvania and Wisconsin.
Friday's legal actions came less than two weeks before the states would have to complete the tasks to meet a federal deadline to certify their election results.
The moves seeking to block or halt the recounts in the states the Republican candidate narrowly won could cause delays that would make them extremely difficult or impossible to complete on time.
The presidential race is decided by the Electoral College, or a tally of wins from the state-by-state contests, rather than by the popular national vote.
READ MORE: Wisconsin starts US presidential election recount
Federal law requires states to resolve disputes over the appointment of electors by December 13.
Trump far surpassed the 270 electoral votes needed to win, with 306 electoral votes, and the recount would have to flip the result to Democrat Hillary Clinton in all three states to change the overall result.
In the popular vote, Clinton won over 2.5 million more votes than Trump, according to the Cook Political Report.
The recounts were requested by Green Party candidate Jill Stein, who says they are necessary to ensure that voting machines were not hacked, even though there is no evidence that they were.
Stein got about one percent of the vote in all three states. Her critics say she is simply trying to raise money and her political profile while building a donor database.
"Our goal is not to change the result of the election," Stein said in an opinion piece released on Thursday. "It is to ensure the integrity and accuracy of the vote."
Wisconsin is the only state where a recount is under way. It began on Thursday, and one of the state's 72 counties had already completed its task by Friday, with Clinton gaining a single a vote on Trump.
|Critics say Stein is simply trying to raise money and her political profile [Reuters]
Clinton lost to Trump in Wisconsin by about 22,000 votes, or less than one percentage point.
Two pro-Trump groups, the Great America PAC and the Stop Hillary PAC, along with Wisconsin voter Ronald R Johnson went to federal court late on Thursday to try and stop the recount.
They requested a temporary restraining order in US District Court to immediately halt the recount while the court considers their lawsuit.
The lawsuit says Wisconsin is violating the US Supreme Court's 2000 Bush v Gore ruling because it does not have uniform standards to determine which votes should be counted in a recount.
They also argue that it threatens due process rights because it may not get done by the federal deadline to certify the vote, putting Wisconsin's electoral votes in jeopardy.
Michigan's elections board were in a deadlock on Friday on a Trump campaign request to deny Stein's recount request and on how a recount would be conducted.
Both Republican members voted to prevent the recount while both Democrats voted to allow it, meaning it would begin Tuesday or Wednesday unless the courts intervene.
It also would be conducted by hand, as Stein requested.
Michigan Attorney General Bill Schuette, a Republican, said on Friday he had filed a lawsuit to halt the requested recount in his state.
Recounting all of the state's votes "threatens to silence all Michigan votes for president" because of an impending federal deadline to finalise the state's results, he said in a statement.
The Michigan courts appeared unlikely to rule immediately, with one asking for a response from state elections officials by Tuesday.
Schuette also criticised Stein for the potential expense of a recount, although she said last week that she had raised $3.5m to cover some costs.
A Schuette spokeswoman said on Friday that Stein had contributed $787,500 but that it would cost about $5m.
In Pennsylvania, a hearing is scheduled for Monday on Stein's push to secure a court-ordered statewide recount there.
Source: News Agencies