"And the Lord brought us forth out of Egypt," not by means of an angel, and not by means of a seraph, and not by means of a messenger. On the contrary, the Holy One, blessed be He, by His own glorious self [did it]...
"For I will go through the land of Egypt," I, and not an angel.
"And will smite all the firstborn," I, and not a seraph.
"And against all the gods of Egypt I will execute judgements," I, and not a messenger.
"I the Lord," it is I and none other.
The Yemenite Jews follow a slightly different Haggadah, one based on R. Saadiah Gaon's rescension in the 9th century CE. Theirs contains an additional midrash on the same topic. Despite a reference in Ginzberg's Legends of the Jews, it isn't that well known, undeservedly so.
I transcribed this from a 1953 Folkways recording of a Yemenite Passover in Jerusalem.
Our rabbis of blessed memory say: When the Holy One, blessed be He, went down against the Egyptians in Egypt, nine thousand myriads of angels went down with Him; some of them angels of fire, some of them angels of hail; some of them angels of shaking; some of them angels of quaking; some of them angels of trembling. Trembling seized all who beheld them.
They said unto Him: 'Master of the World, when a king of flesh and blood goes down to battle, his ministers and servants surround him lest harm befall him.
Now, Thou art the King of Kings and Thou knowest full well that we are Thy servants and they [the Israelites] are the children of thy covenant. Let us go down and make war with them [the Egyptians].'
But He replied: 'I will have no peace of mind until I Myself go down.
I myself in My glory, I Myself in My grandeur, I Myself in My holiness. I am the Lord, I am he, and none other [will go down].