The US Supreme Court dealt the latest blow Tuesday to Donald Trump's effort to overturn his election loss when it denied his allies' attempt to block the certification of votes in key state Pennsylvania.

The nation's highest court, which includes three Trump-appointed justices out of nine, did not explain its decision, and none of the members expressed dissent.

More than a month since the November 3 election, Trump still refuses to concede to Democrat Joe Biden -- who has a seven million-vote lead -- and continues to make baseless claims of fraud.

Trump and his allies have filed dozens of lawsuits in several key states, almost all of which have been thrown out by the courts.

One of them, brought by Republican congressman Mike Kelly, challenged the legality of mail-in ballots in Pennsylvania, a crucial battleground state.

Biden carried Pennsylvania in November's vote, four years after Trump won the state.

After the case was rejected by the state supreme court, the plaintiffs turned to the national Supreme Court, asking it to freeze all electoral operations while they developed their arguments.

In dismissing the case, the Court put an end to the procedure and signaled that it was not inclined to get involved in post-election litigation.

Trump had hoped that the high court, whose bench he has tipped solidly to the right, would intervene in his favor.

In 2000, the Supreme Court halted a recount in Florida, where George W. Bush was only 537 votes ahead of Democrat Al Gore, allowing the Republican to win the election.

The Republican-led state of Texas filed another appeal Tuesday to the Supreme Court, requesting the invalidation of results in four key states, but experts were not optimistic regarding its chance of success.