And Hoshea the son of Elah made a conspiracy against Pekah the son of Remaliah, and smote him, and slew him, and reigned in his stead, in the twentieth year of Jotham the son of Uzziah.

Now Osee son of Ela conspired, and formed a plot against Phacee, the son of Romelia, and struck him, and slew him: and reigned in his stead in the twentieth year of Joatham the son of Ozias.

And make a conspiracy doth Hoshea son of Elah against Pekah son of Remaliah, and smiteth him, and putteth him to death, and reigneth in his stead, in the twentieth year of Jotham son of Uzziah.

And Hoshea, the son of Elah, made a secret design against Pekah, the son of Remaliah, and, attacking him, put him to death and became king in his place, in the twentieth year of Jotham, the son of Uzziah.

Then Hoshea, the son of Elah, conspired and carried out treachery against Pekah, the son of Remaliah. And he struck him, and killed him. And he reigned in his place, in the twentieth year of Jotham, the son of Uzziah.

Hoshea, the son of Elah - One of Pekah's friends, according to Josephus.
The twentieth year of Jotham - According to 2-Kings 15:33 and 2-Chronicles 27:1, Jotham reigned only 16 years. See also the suggestion in the margin. Strangely enough, this first year of Hoshea is also called, not the fourth, but the twelfth of Ahaz 2-Kings 17:1. The chronological confusion of the history, as it stands, is striking.
Uzziah - i. e. Azariah. See 2-Kings 15:1-4.

Hoshea the son of Elah - in the twentieth year of Jotham - There are many difficulties in the chronology of this place. To reconcile the whole, Calmet says: "Hoshea conspired against Pekah, the twentieth year of the reign of this prince, which was the eighteenth after the beginning of the reign of Jotham, king of Judah. Two years after this, that is, the fourth year of Ahaz, and the twentieth of Jotham, Hoshea made himself master of a part of the kingdom, according to 2-Kings 15:30. Finally, the twelfth year of Ahaz, Hoshea had peaceable possession of the whole kingdom, according to 2-Kings 17:1."

And Hoshea the son or Elab made a conspiracy against Pekah the son of Remaliah, and smote him, and slew him, and reigned in his stead,.... Did by him as he had done by Pekahiah, 2-Kings 15:28, this was measure for measure, as the Jews say: and this he did
in the twentieth year of Jotham the son of Uzziah; and yet Jotham is said to reign but sixteen years, 2-Kings 15:33, this must be reckoned therefore either from the time of his being viceroy, and judging Israel in his father's lifetime, 2-Kings 15:5 or this was the fourth year of Ahaz, and the twentieth year, reckoning from the time Jotham began to reign, who is the rather mentioned, because as yet the historian had taken no notice of Ahaz.

Hoshea the son of Elah made a conspiracy . . . and slew him--He did not, however, obtain possession of the kingdom till about nine or ten years after the perpetration of this crime [HALES].
in the twentieth year of Jotham--Jotham's reign lasted only sixteen years, but the meaning is that the reign of Hoshea began in the twentieth after the beginning of Jotham's reign. The sacred historian, having not yet introduced the name of Ahaz, reckoned the date by Jotham, whom he had already mentioned (see 2-Chronicles 27:8).

Pekah met with his death in a conspiracy organized by Hosea the son of Elah, who made himself king "in the twentieth year of Jotham." There is something very strange in this chronological datum, as Jotham only reigned sixteen years (2-Kings 15:33), and Ahaz began to reign in the seventeenth year of Pekah (2-Kings 16:1); so that Pekah's death would fall in the fourth year of Ahaz. The reason for this striking statement can only be found, as Usher has shown (Chronol. sacr. p. 80), in the fact that nothing has yet been said about Jotham's successor Ahaz, because the reign of Jotham himself is not mentioned till 2-Kings 15:32.
(Note: Other attempts to solve this difficulty are either arbitrary and precarious, e.g., the conjectures of the earlier chronologists quoted by Winer (R. W. s. v. Jotham), or forced, like the notion of Vaihinger in Herzog's Cycl. (art. Jotham), that the words בן־עזיה ליותם are to be eliminated as an interpolation, in which case the datum "in the twentieth year" becomes perfectly enigmatical; and again the assertion of Hitzig (Comm. z. Jesaj. pp. 72, 73), that instead of in the twentieth year of Jotham, we should read "in the twentieth year of Ahaz the son of Jotham," which could only be consistently carried out by altering the text of not less than seven passages (viz., 2-Kings 15:33; 2-Kings 16:1, and 2-Kings 16:2, 2-Kings 16:17; 2-Chronicles 27:1 and 2-Chronicles 27:8, and 2-Chronicles 28:1); and lastly, the assumption of Thenius, that the words from בשׁנת to עזיה have crept into the text through a double mistake of the copyist and an arbitrary alteration of what had been thus falsely written, which is much too complicated to appear at all credible, even if the reasons which are supposed to render it probable had been more forcible and correct than they really are. For the first reason, viz., that the statement in what year of the contemporaneous ruler a king came to the throne is always first given when the history of this king commences, is disproved by 2-Kings 1:17; the second, that the name of the king by the year of whose reign the accession of another is defined is invariably introduced with the epithet king of Judah or king of Israel, is shown by 2-Kings 12:2 and 2-Kings 16:1 to be not in accordance with fact; and the third, that this very king is never described by the introduction of his father's name, as he is here, except where the intention is to prevent misunderstanding, as in 2-Kings 14:1, 2-Kings 14:23, or in the case of usurpers without ancestors (2-Kings 15:32, 2-Kings 16:1 and 2-Kings 16:15), is also incorrect in its first portion, for in the case of Amaziah in 2-Kings 14:23 there was no misunderstanding to prevent, and even in the case of Joash in 2-Kings 14:1 the epithet king of Israel would have been quite sufficient to guard against any misunderstanding.)

Twentieth year - The meaning is, that he began his reign in the twentieth year after the beginning of Jotham's reign; or, which is the same thing, in the fourth year of Ahaz, son of Jotham.