President Trump on Friday night decried his initial lead in the presidential race that he watched "miraculously disappear as the days went by" and urged his opponent Joe Biden not to claim victory in the election.

"Joe Biden should not wrongfully claim the office of the President," Trump tweeted. "I could make that claim also. Legal proceedings are just now beginning!"

Biden has been gaining votes in crucial battleground states like Pennsylvania and Georgia, where Trump had early leads because of how each of the candidates' supporters chose to vote -- Trump supporters tended to vote in person, and those votes were counted first, and Biden supporters tended to vote by mail.

"I had such a big lead in all of these states late into election night, only to see the leads miraculously disappear as the days went by," he wrote on Twitter. "Perhaps these leads will return as our legal proceedings move forward!"

Democratic nominee Biden has not claimed the office, but he has predicted victory once the final votes are counted.

On Thursday, Trump told reporters: "If you only count the legal votes, I easily win."

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Earlier Friday, as Biden's lead grew, Trump vowed to keep “fighting,” saying he will use “every aspect of the law.”

“We believe the American people deserve to have full transparency into all vote counting and election certification, and that this is no longer about any single election,” the president said in a statement Friday. “This is about the integrity of our entire election process.”

The Trump campaign has filed a litany of lawsuits alleging procedural violations and illegal voting in nearly every state that has yet to report its final results.

ELECTION 2020 LEGAL BATTLES UNDER WAY AS JUDGES WEIGH IN ON TRUMP LAWSUITS IN KEY BATTLEGROUND STATES

In Nevada, the campaign is suing to stop the counting of what it calls "illegal votes," claiming to have evidence that people who are deceased and nonresidents have cast ballots in the 2020 election.

The Trump campaign alleges there are "tens of thousands" of people who voted in Nevada who are no longer state residents. It said it is not seeking to stop the vote, but rather ensure that every “legal“ vote is counted and that no “illegal” votes are counted. Biden leads in Nevada by about 22,600 votes, with 87 percent of precincts reporting.

The campaign and Republicans are focusing much energy in Pennsylvania, where today the state GOP asked the Supreme Court to step in and ensure ballots received after Nov. 3 are segregated from those received by Election Day. Pennsylvania is allowing ballots that are postmarked by Nov. 3 but arrive up to three days later to be counted.

The petition will go to Justice Samuel Alito, but the state was already segregating these ballots before the emergency appeal was filed.

TRUMP CAMPAIGN BALLOT COUNTING LAWSUITS: WHAT TO KNOW

On Oct. 28, the high court said it wouldn’t fast-track an appeal to block vote-counting after Nov. 3. Alito had written a statement conceding "there is simply not enough time" to issue a pre-election decision.

The court's refusal to issue a fast-track decision does not mean it won't rule in the case. The petition asking for the court's review remains before the justices.

Therefore, Alito could ask the state to respond to the emergency appeal and set a deadline for those briefs to be filed. An order is expected in the coming days.

The Supreme Court could step in to overturn the Pennsylvania Supreme Court in the ruling that essentially changed state election law, and void votes after they have been cast in a state that has the potential to decide the presidential election, which is what Republicans are hoping.

The Trump campaign is also asking the court to stop allowing voters to provide late missing proof of identification on Nov. 9, rather than the 12.

On Thursday a judge ordered the county boards of elections to segregate ballots for which ID was validated by Nov. 9 and ballots with valid IDs between Nov. 9 and 12.

The segregated ballots “shall not be counted until further order of this court.”

However, an appellate court in the state handed the Trump campaign a win Thursday by allowing elections watchers to stand as close as 6 feet away from vote counters to ensure a fair process in Philadelphia.

Still, the Trump campaign alleged that "Democrat" elections workers were blocking their access to vote-counting operations.

"On the heels of this ruling, Democrats are blatantly defying the law. These Democrats are blocking the doors to the counting center and pushing our observers outside the building while they continue to count votes inside with zero transparency. What are they hiding?" Trump campaign attorney Justin Clark said in a statement.

A federal judge denied the campaign's request to stop the vote in Philadelphia over observer access, instead urging the sides to forge an agreement.

Eastern District of Pennsylvania Judge Paul Diamond scheduled an emergency hearing over the suit, before pushing the parties to reach agreement during recess, then ruling that each side could have 60 observers in the vote-counting room as long as they could follow social distancing and must stay behind a barrier.

The campaign had filed an emergency injunction to stop the vote count Thursday afternoon on the grounds of alleged due-process violations, accusing the county Board of Elections of "intentionally refusing to allow any representatives and poll watchers for President Trump and the Republican Party" while they continue to count votes.

Earlier, Clark said the campaign had sued to stop elections officials in Pennsylvania from what they characterize as "hiding the ballot counting and processing from our Republican poll observers."

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Clark said that in Philadelphia and elsewhere elections officials had forced their elections watchers to stand 25-plus feet away to observe the counting process.

Fox News' Ronn Blitzer and Bill Mears contributed to this report.