Rep. Keith Ellison (D-Minn.) speaks during a news conference on Capitol Hill on June 16 to discuss opposition to President Obama's trade deal. (Lauren Victoria Burke/AP)

House Democrats are urging the Obama administration to issue an "updated assessment" on the dangers posed by "violent right-wing extremist groups" within the United States and to bolster the Department of Homeland Security’s division for evaluating home-grown threats, according to a letter obtained Thursday by The Washington Post.

The letter — which is being circulated by Reps. Keith Ellison (D-Minn.) and Raúl M. Grijalva (D-Ariz.) — follows discussions among dozens of House Democrats about how to respond to the mass murder of nine black churchgoers last week in Charleston, S.C., both legislatively and across the federal government.

According to an analysis by Southern Poverty Law Center, a legal and advocacy organization that tracks hate activity, the man accused in the shooting, Dylann Roof, 21, was active in an online white supremacist community.

The letter, addressed to President Obama and Homeland Security Secretary Jeh Johnson, suggests that DHS "allocates a disproportionate amount of money and manpower" toward Islamic extremism while "failing to devote adequate resources to violent right-wing extremism."

Further frustrations are directed at how DHS, then run by Janet Napolitano, handled criticism of its 2009 report on the rise of extremism nationwide. That study drew fire from GOP leaders for what many of them saw as unwarranted attention on gun owners and military veterans. House Speaker John A. Boehner (R-Ohio) at the time called it “offensive and unacceptable.”

In the view of the letter’s authors, “There was so much political pushback that DHS repudiated the study and disbanded the Extremism and Radicalization Branch of the Homeland Environment Threat Analysis Division, the unit responsible for the report. This lack of political will comes at a heavy price of repeated attacks on churches, temples and community centers for African American Christians, Sikh Americans and Jewish Americans."

In 2011, DHS officials acknowledged privately that the department had scaled back its efforts since 2009, cutting down on personnel studying domestic terrorism unrelated to Islam.

The total number of House members who have signed on was unclear as of Thursday, due to the letter still making its way around congressional offices.

Ellison, a five-term House member,  was the first Muslim elected to Congress. Along with Grijalva, he co-chairs the House progressive caucus.

S.Y. Lee, a DHS spokesman, responded to the letter by defending current DHS policies and practices.

“The Department of Homeland Security protects our nation from all threats, whether foreign or homegrown, and regardless of the ideology that motivates its violence,” Lee wrote in an e-mail Thursday. “DHS has been implementing the National Strategy on Empowering Local Partners to Prevent Violent Extremism and its Strategic Implementation Plan since 2011, and has conducted other relevant activities since 2005.

“DHS takes seriously our responsibility to respect and protect the civil rights and civil liberties of the public, including members of any particular groups or ideologies,” Lee added.