Officials with the American Civil Liberties Union of Pennsylvania told Mayor Kenney in a letter Wednesday that recent statements by city lawyers "seem to be setting the City up for conflict with protesters during the Democratic National Convention."

The letter noted that the ACLU has met regularly with city officials involved in planning for the DNC, an event expected to attract tens of thousands of delegates and protesters July 24-28.

"We are concerned that the City Law Department seems to have walked back several statements made earlier about how the City would accommodate protest during the DNC," the ACLU wrote in the letter. "The new positions ... raise serious First Amendment issues."

Protest leaders are expected to meet with the city in a closed-door meeting Thursday, and topics like marching on public streets and sleeping overnight at impromptu campsites in city parks are up for discussion. Last week, NBC10.com reported that campsites in South Jersey are already filling up with pro-Bernie Sanders.

As many as 30,000 protesters could flood FDR Park, across the street from the Wells Fargo Center in South Philadelphia, during the entire week in July.

Their treatment at the park is among the concerns cited by the ACLU in their letter to Kenney.

A Kenney spokeswoman has told NBC10 that the city is "not granting camping permits."

But the ACLU wrote that "in meetings, Police Department officials have told us that they will not expend resources to clear FDR Park at night. ... Will the City allow people to remain in FDR Park overnight during the Convention?"

Other concerns raised include:

- "Rush hour" marches in Center City

- Marches down Broad Street

- Crackdowns on protesters without permits

- Enclosing FDR Park in security barriers

To read the full letter, click here.

The director of the Philadelphia office of the Secret Service, which is managing the event as a National Special Security Event, told NBC10 in an interview last week that the Wells Fargo Center and nearby Xfinity Live! entertainment complex will be enclosed by a security fence. But he could not give details about security at FDR Park.