The War Powers Act of 1973 is not in the Constitution. It is an act of Congress which has 1/3 power in the government. An executive branch ignoring this rule is also a 1/3 power. What would the Supreme Court rule? Until then Congress can only defund the effort.
> What would the Supreme Court rule? <
That’s where it should go, and quickly. I think the Constitution is clear. Congress declares war. Then the president runs the war.
But just what is a war? And as you noted, the War Powers Resolution is not the final word. It does not have the weight of an article of the Constitution.
This is a Supreme Court issue.