Israel is called YHVH's elect in Isaiah 45. In that same passage, YHVH calls an unbelieving gentile, Cyrus, His Anointed, 150 years before Cyrus was a ruler. Now, for sure, Cyrus was no Messiah by any stretch of the imagination, but that doesn't negate that he was considered YHVH's anointed.
The church is called elect in various NT passages.
Angels are even called elect in 1 Timothy 5.
Election does not necessarily have anything to do with salvation or justification. It is a positional status before YHVH. Israel was elected by YHVH to bring forth and preserve His word (every book of the Bible was written by a Jew), reveal YHVH to the rest of the world, and bring forth the Messiah, and also to honor His covenant with Abraham. That doesn't mean all of Israel were "elect" in the sense that Believers are by being individually justified. Israel's election is a corporate election as a nation, as established by the Mosaic Covenant.
In Exodus 19:6, Israel is called a holy nation, just like the church is in 1 Peter 2:9. Israel is a holy nation, corporately, made up only of Jews, both believing and non believing. The Church (body of Messiah) is made up only of believing individuals, both Jew and Gentile, of which ethnic distinctions are no longer valid. Yet both Israel and the Church are elect and holy (set apart for the Lord's purpose).
So it is very reasonable for some to hold that the possible deception of the elect as mentioned by Yeshua in Matt 24 could very well mean the people of Israel. And YHVH will not allow that to happen in total. Hosea 5:15 along with Matt 23:39 make it quite clear that Israel, corporately as a nation, must call out for Yeshua's return before He will do so. The leadership of Israel rejected Messiah, but many of the Jewish people did not. So the leadership has to come around and recognize and call for His return before He can.
That should put an end to the Brit-Am arguments and that the Jewish people make up various nationalities world wide. i.e. the ten lost tribes nonsense. As well as "the church has replaced Israel" stuff.