WASHINGTON: Officials in the election battleground state of Pennsylvania on Thursday asked a federal judge to dismiss a lawsuit brought by US President Donald Trump's campaign seeking to prevent the state from certifying its results in the vote for president.

In court filings in the US District Court for the Middle District of Pennsylvania, lawyers for the Pennsylvania secretary of state and seven of the state's counties said the case made vague and unsupported allegations "on the basis of repeatedly-rejected legal theories and no evidence."

"This Court should see this lawsuit for what it is: a transparent and premeditated attack on our electoral system that broadly seeks to disenfranchise all Pennsylvania voters who legally cast ballots in this election," four of the counties said in a court filing.

Pennsylvania officials said they "administered a proper, fair, and secure election" and would vigorously defend the case. They also said that the plaintiffs lacked standing for their suit.

President-elect Joe Biden, a Democrat, won the majority of the vote in all seven of Pennsylvania's counties cited in the lawsuit and is up more than 53,000 votes with an estimated 97% of ballots counted across the state.

Republican Trump's campaign said the "Democrat-majority counties" did not provide partisan election observers an opportunity to assess the processing of mail-in ballots, placed the observers too far from the tabulation of votes and allowed mail-in voters whose ballots were deficient to cast provisional ballots in what they say was a flouting of the state's electoral rules.

But Pennsylvania officials said the election observers were, in fact, allowed to assess the processing of mail-in ballots and that all of the state's counties were permitted to inform residents if their mailed-in ballots were deficient, even if it was not mandatory for them to do so.

Biden clinched the election on Saturday after media networks and Edison Research called him as the victor in Pennsylvania, putting him over the 270 electoral votes needed to win.

But Trump has refused to concede and has repeatedly and without evidence claimed there was widespread voter fraud. His campaign has filed a string of long-shot lawsuits in several battleground states.

Legal experts say the lawsuits have little chance of changing the outcome of the election. A senior Biden legal adviser has dismissed the litigation as "theatrics, not really lawsuits."

Pennsylvania is due to certify the election results on Nov. 23.