Congress could soon prohibit retailers from selling tobacco products to users under 21 years of age. Lawmakers have inserted a provision into the end-of-year spending bill that would raise the federal minimum age from 18.

President Trump has floated supporting the age increase in the past. Senate Majority Leader Mitch McConnell pushed legislation to that effect.

"Since I introduced my legislation earlier this year to raise the minimum nationwide purchase age for tobacco products from 18 to 21, stories of vaping related illnesses and deaths — especially among young people — have stunned Kentucky and the nation," McConnell said in a statement.

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"I'm grateful to the communities, the health advocates and my fellow elected officials, including President Trump and Senators Todd Young and Mitt Romney, who have joined Senator Kaine and me to address this urgent crisis and keep these dangerous products away from our children," it added.

Nineteen states have already raised the age to buy tobacco products to 21: Arkansas, California, Connecticut, Delaware, Hawaii, Illinois, Maine, Maryland, Massachusetts, New Jersey, New York, Ohio, Oregon, Pennsylvania, Texas, Utah, Vermont, Virginia and Washington, in addition to the District of Columbia.

But it's not the only significant change in the legislation. Also tucked into two large pieces of legislation is funding for $25 million worth of gun violence research at the Centers for Disease Control and National Institutes of Health. Congress hasn't funded gun violence research in 20 years.

Democrats are also touting the legislation's $425 million for election security grants and a $208 million increase in funding for the Environmental Protection Agency to $9 billion.

The 2020 Decennial Census is fully funded in this bill, at $7.6 billion — $1.4 billion more than Mr. Trump proposed. There is also a 3.1% pay raise for federal civilian employees included in the legislation.

Reporting by Alan He and Rebecca Kaplan.