More than half a million people have signed a petition demanding First Lady Melania Trump pay for the cost of her security detail in New York City.

The Change.org petition, which surpassed the 500,000-signature threshold on Monday morning, claims that the first lady’s decision to remain living in NYC’s Trump Tower rather than move to the White House imposes an inappropriate burden on American taxpayers.

The actual cost of Mrs. Trump living in New York is unclear. When President Donald Trump is at Trump Tower, the cost is reportedly around $500,000 per day. The cost is likely far lower when the president is not in New York, which he has not been since the inauguration. The city, not the federal government, has reportedly borne the brunt of the security costs so far.

The issue of Trump’s cost on taxpayers is not limited to the president’s New York City property. Trump regularly travels to his Mar-a-Lago resort in Palm Beach, Florida, at a cost of approximately $3 million per trip, according to CBS News, which based its estimate on similar trips by former President Barack Obama.

The White House has so far refused to reveal the exact cost of the president’s trips to Mar-a-Lago, which has been dubbed the “Winter White House” due to Trump’s frequent visits there.

Mrs. Trump has decided to live in Trump Tower with her 11-year-old son Barron until at least the end of the school year. The White House has said the first lady will split her time between Washington, D.C., and New York City starting this summer.

The Change.org petition now seeks to cross the 1 million-signature mark. The petition’s creators plan to deliver it to Sen. Bernie Sanders of Vermont and Massachusetts Sen. Elizabeth Warren, two of Trump’s staunchest critics in the Senate. However, it remains unlikely that the petition will expedite the first lady’s move to the White House.