Congressional Democrats have begun planning a series of oversight investigations into the Department of Homeland Security (DHS) and Secretary Markwayne Mullin, should the party gain control of the House or Senate in the upcoming November midterm elections. The proposed inquiries focus on the administration’s immigration enforcement policies, agency spending, and allegations of election interference. Rep. Bennie Thompson (D-MS), expected to chair the House Homeland Security Committee if Democrats win the majority, stated that the party intends to investigate what he described as out-of-control immigration policies and corruption.
These preparations follow a period of heightened tension between the agency and Democratic lawmakers. Secretary Mullin, a former Republican senator, assumed the role after the departure of former Secretary Kristi Noem. Recent events, including an October 12 U.S. Immigration and Customs Enforcement (ICE) raid on the residence of Rep. Ilhan Omar (D-MN) and reports of deaths of American citizens following encounters with immigration officers, have intensified calls for congressional review.
Specific areas of focus for the planned committees include the deployment of body cameras for immigration agents, conditions at detention facilities, and the department's level of cooperation with its Inspector General. Lawmakers also plan to review the expenditure of funds from reconciliation bills, specifically citing the purchase of jets for former Secretary Noem and the acquisition of warehouses for detention. Rep. Robert Garcia (D-CA) stated that the House Oversight Committee would prioritize investigating "abuses of ICE and DHS" alongside probes into the Trump family's business dealings.
In the Senate, 34 Democrats led by Sen. Gary Peters (D-MI) sent a letter to Secretary Mullin on Friday, September 25, 2026, accusing the department of actions that undermine the 2026 midterm elections. The senators questioned a DHS claim that 250,000 noncitizens were registered to vote across four states—a figure the agency has not yet documented—and criticized the use of a federal database to check voter rolls. They also raised concerns about a whistleblower report alleging that DHS personnel may be violating state laws through an "Unlawful Voter Initiative."
The scale of the reported issues involves significant taxpayer funds and public safety programs. For example, Senate Democrats have highlighted the potential withholding of anti-terrorism grants by the Federal Emergency Management Agency (FEMA) from states that do not comply with new federal election policies. Such a move would affect state-level emergency management budgets and local security infrastructure. Additionally, the department’s attempt to cross-reference voter rolls against federal databases affects hundreds of thousands of voter registrations, with Democrats warning that inaccuracies in these databases could lead to the disenfranchisement of eligible voters before the November elections.
A change in congressional control would also set a precedent for how the legislative branch monitors the executive’s use of expedited deportation and detention facilities. While a DHS spokesperson stated that "political attacks will not deter DHS from carrying out its lawful mission," the upcoming midterm elections serve as the definitive deadline for these plans. If the House or Senate changes hands, the transition to new committee leadership will occur when the next Congress convenes in January, at which point the formal issuance of subpoenas and the scheduling of public testimony would begin.
DHS and the White House have defended their actions. A department spokesperson called the allegations of election interference "totally false," stating the agency is protecting election infrastructure. White House spokesperson Lauren Bis characterized the Democratic plans as a "witch hunt" and asserted that the administration's focus remains on law enforcement and border security. Tom Homan has also denied allegations that he accepted a bribe from a government contractor.