(Reuters) - The American Civil Liberties Union on Thursday accused the city of Cleveland of taking too long to issue permits to protesters planning demonstrations at the Republican National Convention in July and threatened to sue if the city delays further.

“Delays by the city are effectively blocking groups from exercising their fundamental right to political expression,” Christine Link, executive director of the ACLU of Ohio, said in a statement. “Cleveland is using security planning as a mask to suppress political speech.”

Thousands of demonstrators are expected to converge outside the convention from July 18 to 21 when presumptive Republican presidential nominee Donald Trump is likely to receive the party’s nomination for the Nov. 8 general election.

Raucous protests for and against the candidate have erupted at Trump events during the primary campaign.

Large groups require a parade permit in Cleveland for demonstrations that would obstruct traffic or occur during special events.

City spokesman Dan Williams said permits would be issued “in time for the convention” but he declined to say what date it considered appropriate. He said he was unaware of any permits issued so far.

The normal permitting process could not be expected for the convention because “this is not normal,” Williams said.

The city of Philadelphia, which will host the Democratic convention a week later, has already begun issuing permits, and Cleveland has told protesters they should wait until two weeks before the convention, the ACLU said.

Undue delays may infringe on protesters’ rights to free speech, the ACLU said, suggesting a deadline of June 1.

If Cleveland delays too long, the ACLU would file a lawsuit in federal court and ask for an expedited hearing, Link said in a telephone interview.

Protesters need adequate time to make travel arrangements and rent needed materials such as portable toilets and sound stage equipment, Link said.

The ACLU wrote on behalf of Citizens for Trump, which applied for a permit one month ago, and the liberal activist group Organize Ohio, which has been waiting two months for a permit.

Citizens for Trump anticipates 104 cars and trucks, 100 motorcycles, four horses and at least 5,000 people to participate in its event, while Organize Ohio expects 3,000 to 5,000 marchers, the ACLU said.

Another attorney represents an individual, John Penley, who has said the city has yet to even respond to his request for a permit application, the ACLU said.