Why does it say "Atah Hu Malki Elokim"?
Radak: You did all these wonders with our fathers. Just like You were my King then, also now. And You are Elokim, the true Judge. If so, just like You saved our fathers, save us!
Malbim: You did previous wonders before our ancestors had merits, and not due to the generation's virtue. You did not need to do so for Your name's honor, for You had not yet called Your name on them - "bi'Ymeihem Yemei Kedem" (verse 2). All the more so now that You are Malki Elokim, and You called Your name on us, You should be concerned for Your name's honor [and save us]!
Until now was in first person plural ("b'Azneinu Shamanu Avoseinu" - verse 2). Why does it say "Malki" (first person singular)?
Radak: When it discusses Bnei Galus, sometimes it discusses the individuals in the plural, and sometimes the Klal, in the singular.
Why did he say "Tzave Yeshu'os Yakov"?
Rashi: Also for those who come after us.
Radak: This is like "Ki Mal'achav Yetzaveh Lach" (91:11).
Malbim: If we do not merit that You save us by Yourself, like of old, at least command to save us via a Shali'ach!
