An infinite list and conga line of never-Trumpers and GOP Establishment backstabbers endorsing Harris will not change the mind of average American voters who love their country and who see the GOP Establishment globalists and Democrats trying to destroy the Republic. The betrayal of America by those endorsers is expected; and it is exactly why the opportunist Nikki Haley and Ron DeSantis went nowhere in the Republican primary for president. They are members of and/or supported by all of the Establishment backstabbers. Voters knew that about Haley and DeSantis. Voters weren't fooled.
Long after Trump is gone, America First voters will still decide everything regarding Republican candidates. It's an America First movement that is temporarily led by Trump. The leadership will change, but it will be America First.
There are only about 40 America First Republicans currently in the GOP House and Senate who vote the wishes of their constituency. The rest (well over 150 in the GOP) are compromised in some way -- mostly bribery or cowardice or both -- and they ignore their voters. They will face retribution at some point along the way and lose their seats -- either by being voted out or stepping away as Romney and others have done.
When you give Leftists a dose of their own medicine, they swear that you've poisoned them -- and they are due. They will be screaming to high Heaven over the payback that will come. And don't recognize Heaven unless they are trying to lecture Christians on Jesus, the Bible, spirituality and faith.