The Pennsylvania Democratic Party has sued Donald Trump and an informal adviser to his presidential campaign for their plans to position volunteer observers at polling places on Election Day.

The federal lawsuit, filed Sunday in Philadelphia, accuses Trump's campaign and Roger Stone Jr., a longtime national political adviser, of "conspiring to threaten, intimidate, and thereby prevent minority voters in urban neighborhoods from voting in the 2016 election."

The lawsuit, which loops in the Republican Party of Pennsylvania, is similar to lawsuits filed Sunday by the state Democratic parties in Arizona, Ohio, and Nevada against Trump, Stone, and the state Republican parties there.

Stone, who has been using the Super PAC Stop the Steal to sign up volunteers, said in an emailed statement that he is "honored but the lawsuit is without merit."

Stone said his group is not working with Trump or the Republican Party in its effort to conduct exit polls outside 7,000 polling places with a history of "one-party rule and past reports of irregularities."

"We seek only to determine if the election is honestly and fairly conducted and to provide an evidentiary basis for a challenge to the election if that is not the case," Stone said. "I assume the purpose of this bogus lawsuit is to distract from the voter fraud the Democrats have traditionally engaged in."

Trump's campaign, in a statement, called the lawsuits "long on rhetoric, short on substance." That statement also said Stone is not affiliated with the campaign and that Trump's staff "is doing everything in accordance with applicable law."

The Pennsylvania Republican Party slammed the lawsuit as "intentionally inflammatory" and a "desperate effort."

The Pennsylvania Democratic Party, in the lawsuit, says it is the Republicans that have a tradition of polling place shenanigans.

The party cites a 1982 consent decree agreed to by the Republican National Committee and still in place to "refrain from undertaking any ballot security activities" that are designed to discourage minority voters. And it invokes the Ku Klux Klan Act of 1871, enacted to allow freed slaves to vote.

The lawsuit asks a federal judge to prevent Trump's campaign, Stone's group, and the Republican Party from "funding, encouraging or otherwise supporting, including training or organizing, individuals who are not officially appointed poll watchers under Pennsylvania law."

Trump, in rallies held in Pennsylvania and other states, has exhorted his supporters to travel to urban areas like Philadelphia to watch for voter fraud at polling places on Election Day.

The Pennsylvania Election Code requires poll watchers to be registered to vote in the county where they will serve.

The Pennsylvania Republican Party, in a lawsuit filed Oct. 21, asked a different federal judge to overturn that provision, calling it unconstitutional.

U.S. District Judge Gerald Pappert is expected to rule this week on a Republican request for an injunction, barring the enforcement of that provision.

brennac@phillynews.com

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@ByChrisBrennan