The United States Supreme Court rejected a lawsuit by the Texas attorney general aimed at overturning the presidential election results in several swing states after former vice president Joe Biden was declared the winner.
President Donald Trump supported the lawsuit.
The lawsuit aimed to delay the electoral college vote, a major step in officially confirming a presidential win, in four states that voted for Mr Mr Biden - Georgia, Michigan, Pennsylvania and Wisconsin.
“Texas has not demonstrated a judicially cognisable interest in the manner in which another state conducts its elections," the court stated.
"All other pending motions are dismissed as moot."
This was the most significant legal loss for the Trump campaign and the second rejection by the Supreme Court of the outgoing president’s efforts to upend the election results.
"The Supreme Court has decisively and speedily rejected the latest of Donald Trump and his allies' attacks on the democratic process," said Mr Biden's spokesperson, Mike Gwin in a statement.
"This is no surprise – dozens of judges, election officials from both parties, and Trump's own attorney general have dismissed his baseless attempts to deny that he lost the election."
The Trump team has lost more than 50 legal challenges to the election so far.
The attempt by Texas was backed by 126 Republican Congress members and several Republican state-level attorneys general.
The states that the Texas motion targeted have criticised the effort, with Pennsylvania’s attorney general calling it a "seditious abuse of the judicial process”.
On Monday, electoral college representatives will convene and cast their official votes for president and vice president in the final step to certify Joe Biden and Kamala Harris’s win before the inauguration on January 20.
The court's decision is a devastating blow to Mr Trump's continued challenges to the election results.
The president tweeted earlier Friday that the lawsuit could be the "most important case in history".
Mr Trump has still not formally conceded to Mr Biden.
"President-elect Biden's clear and commanding victory will be ratified by the electoral college on Monday, and he will be sworn in on January 20," Mr Gwin said.