"Of course, where an emergency exists, a President may decide that principles more fundamental than the Constitution’s appropriations requirement justify spending. For instance, at the outbreak of the Civil War—with the Nation itself at risk—Lincoln ordered the expenditure of two million dollars in federal funds in advance of appropriations.
Moreover, despite the categorical imperative of the Appropriations Clause, it would seem that
Congress itself is constitutionally obligated to provide funding necessary for the President to undertake executive powers specifically granted in Article II—to receive ambassadors, act as Commander in Chief, negotiate treaties, and the like. If Congress fails to provide necessary funds,"
Interpretations of Appropriations Clause by constitutional scholars
constitutioncenter.org
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He shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur; and he shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls, Judges of the supreme Court, and all other Officers of the United States, whose Appointments are not herein otherwise provided for, and which shall be established by Law: but the Congress may by Law vest the Appointment of such inferior Officers, as they think proper, in the President alone, in the Courts of Law, or in the Heads of Departments.
The President shall have Power to fill up all Vacancies that may happen during the Recess of the Senate, by granting Commissions which shall expire at the End of their next Session."
The original text of Article II of the Constitution of the United States.
constitution.congress.gov
