The Senate Appropriations Committee is about to get two new subcommittee chairmen after the top Republicans on the Financial Services and Legislative branch panels got approval to serve rare double duty on the Appropriations and Finance panels.

“There will be some changes,” Senate Appropriations Chairman Richard C. Shelby said Tuesday when asked whether Sens. Steve Daines, R-Mont., and James Lankford, R-Okla., would continue in their previous roles. “When they went to Finance they lost their seniority. They knew that.”

Added Shelby: “So, you can’t have your cake and eat it too.”

Senate Majority Leader Mitch McConnell, R-Ky., announced last week that Daines and Lankford would hold seats on both plum committees, widely considered the most powerful in the Senate.

They would be the first senators since 1944 to hold that distinction, putting them on the committee in charge of raising revenue for government programs, Finance, and spending it, Appropriations. In fact, Finance controls even more spending than Appropriations because of its jurisdiction over mandatory Social Security, health care and income security benefits.

Assignments to more than one of the “Super A” committees — Appropriations, Armed Services, Finance and Foreign Relations — are barred by Senate GOP Conference Rules. Daines and Lankford were both granted waivers.

Daines was chairman of the Legislative branch panel and Lankford headed the Financial Services panel in the previous Congress.

Based purely on seniority, it is likely that Sens. John Kennedy, R-La., and Marco Rubio, R-Fla., would receive Appropriations subcommittee chairmanships for the 116th Congress.