Senator Kirsten Gillibrand is the first Democratic senator to say that she will vote against a waiver needed for General James Mattis to become Donald Trump’s Secretary of Defense.

A waiver will be required for Gen. Mattis due to a law dating back to 1947, which places a seven year period between the time an individual has left military service and can be appointed as the Secretary of Defense. Mattis retired from the military in 2010 and falls just short of the seven-year requirement.

Since the law was passed in 1947, Gen. George Marshall was granted a waiver and was the last and only defense secretary to receive one.

Despite Senator Gillibrand’s refusal to vote for the waiver, it’s likely the retired general will receive one. Republicans need only eight Democrats to get the waiver passed and Mattis is a well-liked and respected figure.

Senator Gillibrand is a member of the Armed Services committee, which is chaired by Senator John McCain and who fully supports Gen. Mattis for the position. Saying in a statement on Thursday, “America will be fortunate to have General Mattis in its service once again.”

Of course, Republicans should be mindful of the precedent that unabashedly supporting a waiver sets. Democrats have already begun to lament their use of the nuclear option and eliminating the filibuster during their years in the majority in the Senate. Those in the majority should always be prepared to be back in the minority and act accordingly.