The president exercises a check over Congress through his power to veto bills, but Congress may override any veto (excluding the so-called "pocket veto") by a two-thirds majority in each house. ... The President is not mandated to carry out the orders of the Supreme Court.
Or what the other person said
The Constitution entrusts certain powers to the Senate alone. The President may only nominate for appointment Cabinet officials, judges, and other high officers "by and with the advice and consent" of the Senate. ... Madison, holding, however, that Congress could not grant unconstitutional power to the Court itself.
