How do you think “third parties” work?
The last time a third party candidate won electoral votes was in 1968. George Wallace. Running on a segregationist platform. Segregation was popular among the white electorate of certain deep south states, and political poison everywhere else.
There isn’t another issue both as divisive and as localized as Jim Crow, that isn’t supported by either major party, that would leave an opening for a regional third party to win states.
Yes, there are divisive issues. And nowadays usually the Republicans are one one side, and the Democrats on the other. And if they aren’t, then you get things like Donald Trump popping up and winning the Republican nomination despite not following the party line on dozens of issues.
If an issue really is that popular but opposed by both parties, eventually someone will try to capitalize on it. Except segregation wasn’t the issue of the future, 4 years later in 1972 check out the electoral map. Nixon wins in an epic landslide. What happened to all those southern segregationists? They all decided to vote Republican. And then in 1976 the Southerners for a minute remembered that the Republicans were the party of Lincoln and they all turned blue. For the last time. Reagan wins the south in 1980 and 1984, and by 1988 the political revolution is complete and the South is solidly Republican.
What happened in 1992 was the finalization of the party realignment. Even in the 1980s there were still conservative southern Democrats and liberal northern Republicans. But that didn’t matter much, because the Democrats had held Congress for so long that the parties were nearly meaningless. The so-called “bipartisanship” of the era just meant that because the Democrats controlled everything, being a Democrat didn’t mean much, most votes weren’t along party lines because if they were then the Democrats would win handily.
Then along came Newt Gingrich. After holding the house for generations the Democrats were finally ousted, and the Republicans who took charge felt they had an explicit ideological mandate for change.
Yes, it’s all a conspiracy among the powerful. Except it’s not secret. The ideological realignment is very well known and out in the open. The conspirators are people like Reagan and Jesse Helms and Gingrich and Bill Clinton, all of whom shaped and molded the political landscape in various ways to result in the morass we have today.