1)
Why does it say "Az Yechalek"?
1.
Malbim: While Zimri was alive, they were united against Zimri. Even though those who did not want Amri did not separate, lest Zimri overpower. Once he died, there was a division.
2)
Why does it say "ha'Am Yisrael"?
1.
Radak: The word that should be Samuch [to Yisrael] is omitted. This is like "ha'Aron ha'Bris" (Yehoshua 3:14). 1
1
Radak (Yehoshua 3:14): The word "Aron" is written only once, but it is as if it is written twice - Nos'ei ha'Aron, Aron ha'Bris. (Also here, we can say that it is as if it is written ha'Am, Am Yisrael. - PF)
