A federal panel reviewing Donald Trump’s planned $400m ballroom addition to the White House postponed an expected vote on the project until next month, after receiving thousands of negative public comments.

The National Capital Planning Commission (NCPC) had been expected to cast a final vote on the proposal on Thursday, but instead, the chair of the commission announced at the beginning of the meeting that the vote would now be held on 2 April, citing the “large amount of public input” submitted during the public comment period.

“We’re going to take the time to deliberate, and we’re going to have a final vote on April 2,” Will Scharf, the NCPC chair and top aide to Trump, said on Thursday as the meeting began, according to CNN.

Before the meeting, the commission released more than 9,000 pages of public comments it received about the project. The commission has said that more than 35,000 people had submitted written comments, with the majority opposing Trump’s plans to build a 90,000 sq ft ballroom where the East Wing of the White House once stood, and condemning the demolition of the East Wing that began in October.

At the time, White House officials argued that demolition did not require the commission’s approval, and said they would present plans for any construction proposals to the proper commissions. Trump has said the ballroom will cost around $400m and be financed with private donations.

A recent analysis by the New York Times found that more than 98% of the roughly 32,000 submitted comments opposed the plan, with respondents describing the proposed design as “gaudy and cheap”.

The White House did not immediately respond to a request for comment from the Guardian on the delayed vote on Thursday.

In a statement to the New York Times, Karoline Leavitt, the White House press secretary, said that the negative comments submitted about the ballroom “are clearly stemming from an organized campaign of Trump-deranged liberals who clearly have no style or taste”.

The postponed vote comes as Trump has appointed allies to positions on the NCPC commission. Earlier this week, the NCPC executive director published a recommendation that the commission “approve the preliminary and final site and building plans for the East Wing Modernization Project, located on the grounds of the White House”.

The Commission of Fine Arts, which is also tasked with reviewing the ballroom plans and where Trump has also installed loyalists, voted to approve the ballroom project last month.

Historic preservationist groups have sued and attempted to halt the project. In December, the National Trust for Historic Preservation filed a federal lawsuit, seeking to block the construction of the new ballroom, arguing that the administration violated multiple laws by tearing parts of the White House “without any review whatsoever”.

A federal judge declined to temporarily halt construction last week. The group has said it plans to file an amended lawsuit.

The Associated Press contributed reporting