US President-elect Joe Biden's win in Wisconsin has been reaffirmed after two of the state's largest counties completed the recount of the ballots cast in the November 3 presidential election, with just a little change in the tally.

The Democratic former Vice President's lead over incumbent President Donald Trump in the key swing state grew by 87 votes, after the latter gained 45 votes in the Dane County recount and Biden got a 132-vote net gain in the Milwaukee county recount, Xinhua news agency reported.

The statewide tally showed Biden won Wisconsin by over 20,000 votes.

The Trump campaign has, as required by state law, paid $3 million for the recount, only to see his defeat more apparent.

A day before the recount results, Trump had tweeted on Saturday that he would file a lawsuit "Monday or Tuesday" to continue challenging the results.

"The Wisconsin recount is not about finding mistakes in the count, it is about finding people who have voted illegally," he said.

"We have found many illegal votes."

Wisconsin is set to certify the results on Tuesday.

Wisconsin Voters Alliance, a conservative voter group, has filed a lawsuit against the Wisconsin Elections Commission, asking the state's Supreme Court to prevent the certification.

But Wisconsin Governor Tony Evers' attorneys filed a response to the lawsuit on November 27, calling the group's effort a "brazen attack on democracy itself" and asked the state Supreme Court to dismiss it.

The Democratic Governor said the lawsuit was a "mishmash of legal distortions" that attempted to disenfranchise millions of Wisconsin residents.

He said failing to certify the election results would alter other election results across the state, throwing the government into chaos.

Trump also suffered consecutive legal defeats in Pennsylvania, as the state's Supreme Court on Saturday ruled against a Republican-filed case alleging voting irregularities, after a federal appeals court denied his re-election campaign's effort to appeal its own case that was rejected by a lower court.

Trump told Fox News on Sunday that he "would like to file one nice big beautiful lawsuit" in the US Supreme Court, complaining that "it's hard to get into the Supreme Court".

He said the high court needs to be "willing to make a real big decision", adding he's got "the best Supreme Court advocates, lawyers that want to argue the case if it gets there".

Last week, US District Judge Matthew Brann rejected the Trump campaign's lawsuit accusing Pennsylvania of allowing voters to fix errors in the mail-in ballots and seeking to prevent the state from certifying the results.

The judge also refused the campaign to file an amended complaint.