Former Vice President Joe Biden this week endorsed the campaign of transgender candidate Danica Roem.

Roem is working to unseat Virginia Delegate Bob Marshall, a Republican from Prince William County and a vocal opponent of LGBT rights.

“As someone who spent decades riding the train to work, I’m proud today to endorse Danica Roem’s historic candidacy because I know her emphasis on improving transportation infrastructure is critical to improving the quality of life for thousands of Virginians,” said Biden in a statement to the Democratic Party of Virginia. “I know she’d make people of her lifelong home of Prince William County proud by working to improve their commutes and strengthen the middle class while serving them with compassion in Richmond and Manassas.”

In a statement given to the Democratic Party of Virginia, Roem, a journalist, said that she is “humbled” by Biden's endorsement.

The Victory Fund, which backs LGBT candidates for public office, praised the move in a statement.

“Former Vice President Joe Biden’s endorsement signifies the importance of this race not just to Virginia, but to the entire nation,” said Victory Fund President & CEO Aisha C. Moodie-Mills. “Danica Roem is transcending the divisive politics of today by knocking on doors and focusing on issues that will improve the lives of her constituents. Yet a win for Danica will also send a powerful message to elected officials nationwide: LGBTQ people will target and run against those who attack our community, and we will remove them from power.”

Earlier this year, Marshall, who is serving his 13th term, introduced a bill that sought to prohibit transgender people from using the bathroom of their choice.

(Related: Social conservatives running anti-transgender robocalls against Danica Roem.)