Immigration and Customs Enforcement could run out of money as soon as next month amid the Trump administration’s ramped-up efforts to deport unauthorized immigrants.

While there are more than three months left in the fiscal year, one estimate has found that the agency is already $1 billion over budget, according to Axios. Legislators in both parties have raised concerns about the speed at which the agency is spending its funds, which may prompt President Donald Trump to seek additional funds from other agencies to support his deportation efforts.