Donald Trump was correct to stay in the Republican party. Electoral success comes when you let the other party split... and perhaps even encourage it. As Trump often said; "What the Democrats did to Bernie Sanders was criminal!"
Bull Moose Party Born on the evening of June 22, 1912.
Former President Theodore Roosevelt asked his supporters to leave the floor of the Republican National Convention in Chicago. Republican progressives reconvened in Chicago’s Orchestra Hall and endorsed the formation of a national progressive party. When formally launched later that summer, the new Progressive Party chose Roosevelt as its presidential nominee. Questioned by reporters, Roosevelt said he felt as strong as a “bull moose.” Thenceforth known as the “Bull Moose Party,” the Progressives promised to increase federal regulation and protect the welfare of ordinary people.
Roosevelt maintained that President William Howard Taft had allowed fraudulent seating of delegates in order to capture the presidential nomination from progressive forces within the party. However, the rift between the progressive and conservative wings of the Republican Party was apparent even before Roosevelt left office. Roosevelt’s support of government regulation, his efforts in conservation and consumer protection, and his willingness to work with organized labor alienated pro-business party members.
When Roosevelt tapped Taft as his successor in 1908, he had assumed that Taft would continue to support his agenda. Although Taft’s record suggested a leader sympathetic to reform, the former jurist’s quiet demeanor and attention to the letter of the law irritated Roosevelt and disappointed Republican progressives.
Roosevelt ran for a third term in 1912—in a presidential campaign that was bitterly fought and easily won. With the Republican Party divided, progressive Democrat Woodrow Wilson captured the presidency handily. Although he failed to become chief executive again, Roosevelt succeeded in his vendetta against Taft who received just twenty-three percent of the popular vote compared to Roosevelt’s twenty-seven percent.
Despite an impressive showing in 1912, the Bull Moose Party failed to establish itself as a viable third party. Still active on the state level, Progressives did not put forward a presidential candidate again until Wisconsin Senator Robert M. La Follette‘s run in 1924.
I discovered the Bull Moose Party.
I alone discovered the Moose--
and it would have been a great party
if the people hadn’t discovered the Bull…
But you must admit that the Bull Moose Party during its short but eventful life served this country well.
If it wasn’t for us and mostly me—you wouldn’t have Woodrow Wilson as your president to-day.
Suppose I hadn’t taken the stand I did in Chicago!
Where would we be now?
I had no feeling against Mr. Taft.
He’s a brilliant man—honorable—the highest type of intellectual American but he had one unpardonable fault--
he wouldn’t do a damn thing I said.
The first decades of the twentieth century were marked by unprecedented efforts at social and governmental reform. Presidents were chosen from the far left (Wilson), and far right (Coolidge).
While voters finally rejected the radical socialist direction of the US, the damage done to the US Constitution was never recovered (except the ending of liquor prohibition).
As Ronald Reagan famously said; "The closest thing we have to eternal life, in this world, is a federal program.".
The states' rights influence deeply declined when legislatures lost their power to appoint 2 delegates to the US Senate. But more importantly, the US Federal power to tax individuals was established by removing the constitutional ban on individual taxation. Prior to that, states were assessed a tax, and the states, in turn, taxed their own citizens.
For leftists like Teddy Roosevelt & Woodrow Wilson, the 1912 election was assured for socialists, because they were able to split the party of the right.
But for the decades of the mid 20th century, the Republican Party was split between the conservatives like Coolidge, Goldwater, and Reagan; and economic Fascists like Teddy Roosevelt, Prescott Bush, Nelson Rockefeller, & George Romney. The Romneys & Bushes continued to exploit the GOP well into the 21st century.
The Democrats did have a conservative faction, like George Wallace, Strom Thurmond, & John Kennedy. But racist policies discredited some of them.