Sen. Markwayne Mullin’s (R-Okla.) nomination to lead the Department of Homeland Security (DHS) on Thursday advanced out of the Senate Homeland Security and Governmental Affairs Committee despite reservations from Democrats and the committee’s Republican chair.

Senator Markwayne Mullin faces a challenging Homeland Security Committee vote for his DHS Secretary nomination after a heated exchange with Senator Rand Paul, who will vote against him.

If confirmed, Mullin will lead a department of more than 260,000 employees that oversees critical agencies including Immigration and Customs Enforcement, the Transportation Security Administration and...