Mdd, see http://www.hebrewbooks.org/pdfpager.aspx?req=14388&hilite=e7539dd1-d1d6-46fd-8b6d-66a2c821025c&st=%D7%A7%D7%91%D7%95%D7%A5&pgnum=329. Why should there not be l’chatchila and b’diavad in this mitzva? Really, there should be no need for any type of government. Hashem should be King. That is to say, people should keep mitzvot without compulsion. Forming a government is a tacit admission that the people are not capable of that (Shmuel Alef 18,7). If there is to be a government it depends on how far the people have descended. If the situation is not too bad a republican form of government is appropriate – and this was the case in the autonomous medieval kehillot. If it is worse a constitutional monarchy (the king is subject to the limitations of the Torah as expounded by the Sanhedrin and the nevi’im) is needed. However, this is only if there is a someone worthy of the tremendous powers which a king has (Rambam Hilchot Melachim ch. 3, 8-9). As Abarbanel points out, we see what happened immediately after the death of Shlomo. The bad kings brought Am Yisrael down to the three cardinal sins by example.
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