Rashi: He was silent.

Radak: It is Nif'al conjugation, Po'el Omed (the action applies only to the subject). It is cutting, like I explained "Nidmu Ami" (4:6). The king was cut off in Shomron. He was besieged many days, and could not be saved from Melech Ashur, and went quickly to Galus.

Malbim: It resembles. Yisrael is ashamed of its counsel, for it caused Melech Shomron to be compared to foam on water. When water is boiled below, there is foam on top, and it disappears (evaporates). So the king, via the nation's agitation, anger and rebellion against the previous king, they conspired with Hoshe'a against Pekach ben Remalyahu and killed him, and Hoshe'a ruled in place of him. Afterwards the foam went to Galus via the nation's slander and changing mindsets - their heart does not remain in one state. This counsel did not succeed to strengthen Avodas ha'Egel - just the contrary, it ceased the Avodah!

Rashi, Targum Yonasan: It is foam.

Radak: It is the bark on a tree, like "u'Se'enasi li'Ktzafah" (Yo'el 1:7).