A personnel change in Donald Trump's administration has thrown the Republican Party into crisis, with representatives claiming they have lost their Senate and House mediator. Shifting Sen. Markwayne Mullin’s (R-Okla.) to the Department of Homeland Security to replace Kristi Noem has worried some GOP members. Reps believe Mullin will be hard to replace in the Senate as his drive for open dialogue between the House and Senate is a crucial part of the GOP's work. Though it is an informal role, there are some in the party who, when speaking to The Hill, suggested there is no replacement for Mullin. Sen. James Lankford (R-Okla.), who had served in the House prior to his Senate appointment, worried there would be no way of bringing a Mullin-like figure to unite the GOP teams in the House and Senate. He said, "People outside of D.C. think the north side of the building and the south side of the building talk to each other all the time and … that’s not true. It’s hard to be able to maintain relationships across the building because our schedules are different, we function different, the structure of how we actually operate is so different."Markwayne had really good relationships in the House and the Senate, and that’s going to be tough. It’ll be a loss for the Senate for him going into this position, but it’ll be a gain for the country for him to be able to do it."Sen. Kevin Cramer noted Mullin "loved to be in the mix" with both the House and Senate, and a clear replacement for the GOP in this unofficial role.Some GOP reps believe Mullin is irreplaceable in this unofficial role, and that moving him to serve under Trump directly is a major blow ahead of the midterms. Sen. Katie Britt (R-Ala.) said, "Nobody’s going to be able to do what he’s done. We have a number of members who have great relationships in the House. I think that they will, obviously, elevate those. … It’ll take a lot of people to fill the role of one person, and because it’s not just one person, there’s a connectivity issue there."