Is oath is to the constitution and his obligation is to not enforce laws that are unconstitutional.
Yes, VRWC_minion.
However, it's not just enforcing already passed laws,
or actively refusing to enforce bad laws.
His oath also requires signing into law bills that are NOT un-Constitutional.
Every time he signs an un-Constitutional bill into law,
or fails to veto an un-Constitutional bill,
the President violates his oath.