By Andrew Chung and Lawrence Hurley
(Reuters) - The U.S. Supreme Court on Wednesday dealt setbacks to Republicans by allowing extended deadlines for receiving mail-in ballots in next Tuesday's election in Pennsylvania and North Carolina, states pivotal to President Donald Trump's re-election chances.
The action by the justices - with their new colleague Amy Coney Barrett remaining on the sidelines - means a Sept. 17 ruling by Pennsylvania's top court allowing mail-in ballots that are postmarked by Election Day and received up to three days later to be counted will remain in place for now.
The Supreme Court already had rejected a prior Republican request to block the lower court ruling on Oct. 19. This time, the justices opted not to fast-track their consideration of an appeal of the state court ruling by the Republican Party of Pennsylvania to hear and decide the case before the election.
The conservative-majority court on Wednesday also rejected a request by Trump's campaign to block North Carolina's extension of the deadline for receiving mail-in ballots, in another key battleground legal loss for Republicans.
Pennsylvania is being closely contested by Trump and his Democratic challenger Joe Biden. Trump won Pennsylvania in 2016 but is now trailing Biden there in many opinion polls.
Barrett, a Trump appointee who joined the court on Tuesday, did not participate in Wednesday's decisions. She did not have time to fully review the filings in the cases, a court spokeswoman said in a statement.
Justice Samuel Alito, joined by fellow conservatives Clarence Thomas and Neil Gorsuch, said in a written opinion that there is a "strong likelihood" that the Pennsylvania court's decision violates the U.S. Constitution and it should be reviewed before the election.
"But I reluctantly conclude that there is simply not enough time at this late date to decide the question before the election," Alito wrote.
Pennsylvania Attorney General Josh Shapiro, a Democrat, in a statement urged voters to drop off mail ballots at drop boxes or county election offices in an effort to "stave off further anticipated legal challenges."
The Pennsylvania Supreme Court ruled in favor of the Pennsylvania Democratic Party and various Democratic officials and candidates who had asked for the court to protect voting rights during the coronavirus pandemic.
Democrats in the case also raised concerns about whether the U.S. Postal Service, led by a Trump ally, would be able to handle the surge of ballots in a timely manner.
On Monday, the conservative justices were in the majority when the Supreme Court on a 5-3 vote declined to extend mail-in voting deadlines sought by Democrats in Wisconsin.
The conservative justices indicated they did not see the Pennsylvania matter as closed.
They said the case still could be reviewed and decided relatively quickly. Pennsylvania officials have said that ballots arriving after Election Day will be kept separate from the other ballots "so that if the State Supreme Court's decision is ultimately overturned, a targeted remedy will be available," Alito wrote.
Trump's fellow Republicans in many states have opposed measures to facilitate voting during the coronavirus pandemic. The public health crisis has prompted an increase in requests for mail-in ballots as voters seek to avoid crowds at polling places.
In their earlier decision, the justices, shorthanded after the death of Justice Ruth Bader Ginsburg, were divided 4-4, leaving in place the state court ruling. Chief Justice John Roberts joined the three liberal justices in denying the request.
Trump has attacked the integrity of mail-in voting, a regular part of American elections.