Sessions joins Sens. John McCainJohn McCainMcCain: Trump's withdrawal from TPP a 'serious mistake' Trump signs executive actions on TPP, abortion, federal hiring freeze Rubio to vote for Tillerson MORE (R-Ariz.) and Lindsey GrahamLindsey GrahamRubio to vote for Tillerson Top Dem comes out against Tillerson ahead of key vote Schumer, Cardin to introduce legislation on Russia sanctions MORE (R-S.C.) in opposing the sequestration of defense funding. On Monday, those two senators released a statement that said the cuts "cannot be allowed to occur."

McCain in particular has argued that the required cuts would come on top of the $350 billion in cuts that Defense already faces, and nearly $200 billion in other reductions that former Defense Secretary Robert Gates imposed.

Sessions said that the Defense Department makes up about one-sixth of the federal government, and therefore should not have to shoulder half of the $1.2 trillion sequester. McCain and Graham said they are looking for ways around these cuts, and House Armed Services Committee Chairman Buck McKeon (R-Calif.) said he is preparing a bill for that purpose.