'Able to Deliver' in the Bible

Thus saith the king, Let not Hezekiah deceive you: for he shall not be able to deliver you.

They have stooped, they have bowed together, They have not been able to deliver the burden, And themselves into captivity have gone.

Who is this who comes from Edom, dressed in bright red, coming from Bozrah? Who is this one wearing royal attire, who marches confidently because of his great strength? "It is I, the one who announces vindication, and who is able to deliver!"