Tzaddikim could decree Moshiach -- why don't they?!

Sicha Parshas Pinchas 5744

The truth is that if the tzaddikim of the generation decided to bring the redemption, they would certainly do so, for “the tzaddik decrees and G-d fulfills.” But as long as G-d wants the Jews to be in exile, the tzaddikim listen to Him. This is self-sacrifice of the highest order: The redemption is something that is vitally necessary, and yet they don’t decree it because of G-d’s will. But the question still remains — until when?

At any rate, when Jews perform their service in the manner of redemption, they effect the actual, literal redemption from Above, since G-d pays “measure for measure.” Since the redemption comes from Above, through G-d Himself in all His glory, it will certainly be a true and complete redemption — just as G-d embodies the absolute truth and the absolute perfection. Also, since it is G-d who brings the redemption, there will be no time constraints, and Jews will be “redeemed immediately.