There's a lot of voter rage directed at the GOP. Problem is, that's misdirected.
It's not that there aren't some real stinkers in the GOP leadership. To take a few current examples, governors who fold on religious liberty, viz. Nathan Deal, Mike Pence, Asa Hutchinson–as well as Sen. Portman.
However, the GOP leadership is not the source of the problem. It's a symptom, not the cause. Angry voters are fixated on a symptom.
The GOP is like a pyramid. The fundamental weakness isn't at the top but the bottom. The base of the pyramid is too small. The reason we have some duds in leadership positions is because there aren't the votes to replace them to stalwart conservatives. There aren't enough rightwing voters to run the table.
In a country as diverse and populous as the US, to be a viable national party, you have to attract a coalition of different voting blocks. There aren't enough rightwing voters to float a viable national party. That voting block is too small all by itself.
This is a problem with furious voters who wish to raze the GOP. They hope to replace it with an ideologically pure third party. They act as though the GOP is a granite slab that's suppressing the silent rightwing majority. But unfortunately, no such majority exists.
A third party might indeed be ideologically purer, but it would be purer at the expense of being much smaller. It wouldn't be competitive. Smashing the GOP just reshuffles the same deck. It doesn't add new conservative voters to the deck. It merely rearranges the same basic number of voters. You are still stuck with same basic ideological spread.
Instead of subdividing the deck two ways, between hearts and diamonds, it subdivides the decks three ways, into spades, hearts, and diamonds (or clubs, as the case may be). Regrouping the same number of cards into smaller sets.
Indeed, if conservatives abandon the GOP for a third party, the GOP will cease to be politically viable. In that event, the remaining Republicans will probably join the Democrats. After the dust settles, you'd wind up with a larger Democrat party, and a smaller opposition party.
To take another comparison, consider Israel, with its Parliamentary system. It has ideologically purer parties, but that's because they are splinter groups. All the parties are weaker.