Secretary of Homeland Security Markwayne Mullin is jumping back into the thick of GOP infighting on Capitol Hill as he tries to speed up funding for the embattled agency he took over in the middle of a partial government shutdown.

Mullin, who left the Senate in March to run the Department of Homeland Security, has been away from the Capitol for just a handful of weeks, but his personal stake in reopening the agency has him reprising a role he often played as a senator: mediator for congressional Republicans.