A group of Democratic members of Congress from New York on Wednesday called on President Biden to invoke the Defense Production Act to enhance the production of vaccines for monkeypox.

In a letter to Biden, the lawmakers, led by New York Democratic Reps. Jerry Nadler and Ritchie Torres, said ,”It is clear that vaccine demand is quickly outpacing supply throughout the country.”

According to the most recent data from the Centers for Disease Control and Prevention, more than 12,000 monkeypox cases have been confirmed in the U.S. so far.

“In New York, every vaccine appointment has been taken. According to [the Department of Health and Human Services], the government is now distributing about 1.1 million doses, less than a third of the 3.5 million that health officials now estimate are needed to fight the outbreak. It is reported that HHS does not expect the next delivery, of half a million doses, until September,” the lawmakers wrote, noting that most of the other doses that have been ordered are not expected to be available until next year.

There are currently two smallpox vaccines being used in the U.S. to mitigate the spread of the monkeypox virus, the more widely favored Jynneos vaccine and the older generation ACAM2000 vaccine.

The New York delegation noted that the Defense Production Act is often used to address national issues and supply shortages. In May, Health and Human Services Secretary Xavier Becerra invoked the act to address the national baby formula shortage.

The limited supply of Jynneos has resulted in many people being unable to receive doses of the vaccine.

The Food and Drug Administration last week authorized dividing doses of Jynneos into fifths and injecting them intradermally, between layers of skin, to stretch the available supply. Bavarian Nordic, the Danish company that makes Jynneos, has expressed concerns about this approach.

“The United States has the resources available to effectively combat the spread of monkeypox, and we owe it to the communities most vulnerable to public health threats to ensure that they are well-protected,” the lawmakers wrote. “Though it is encouraging that the official declaration of a [public health emergency] will accelerate the production and availability of vaccines, tests, and treatments, we must take all available actions to combat this outbreak.”

Other Democratic members of Congress from New York who signed the letter were Reps. Jamaal Bowman, Carolyn Maloney, Alexandria Ocasio-Cortez and Hakeem Jeffries.