Unlike it is now, liberals and leftists can discuss politics together and even go to dinner.
There are no hard feelings towards another, and if the candidate from the opposite group was able to come up with more presentable ideas, there is usually a general acceptance, no divide between the democrats and republicans since there was a consensual understanding.
But what changes, why the noticeable division?
First, it is worth considering that even though media corporations in the United States use the words liberal, leftists, and Democrats synonymously, these words are not relatable.
While Democrats are a party and they are far-right, leftists and liberals are ideologies.
Let us consider the differences between liberals and leftists
Leftists and liberals both pursue a similar goal.
They both want better working conditions, affordable utilities and frowns at inequalities, but there are degrees to these, while liberals want reduced inequalities between the rich and the poor, a leftist demands zero inequality.
From the inferences so far, we can easily see the similarity between both ideologies and conclude that they can easily cooperate.
Since they both pursue a similar goal, why not join forces to fight their common enemy.
The Denialists.
But this is quite impossible since there are still some striking differences between the two ideologies, to get more insight, let consider their history.
The liberals
Liberalism, dated back from the 1840s in England is a party platform, established when a group of politicians proposed a differing set of ideas from their colleagues The Tories and the Whigs.
Unlike the Tories and Whigs which favors landowners and merchants respectively, their ideologies also are not favorable to England’s economic climate at that time.
The new liberal group consisting of the likes of William Gladstone and Richard Cobden embraces wealth through industrialization over capitalist owners.
They encourage free trade rules and low taxes to enable a fast-paced industrialization process.
The government of the liberals for Britain then is just to ensure smooth commerce, while staying out of the way.
The liberals eventually replaced the Whigs and Tories and continues for the next 70 years.
But this will soon change in the 20th century when a new party arose, the labor party.
Arguing that the Liberals encourages poverty by not doing what is needful to help those struggling.
The labor party consisting of the likes of Kier Hardie and Scotish M.P argues that the liberals encourage big pay for the industrialists while leaving the workers to struggle with little aid from the government, they were able to take over liberals and rule Britain from the mid-1920s.
Their ideologies is what we can consider leftist in The US.
They expand income tax from the later 1940s onward, created disability insurance, and ensure free health for all, after World war II, by ensuring the creation of the National Health Service.
The leftists
The economic intervention began to take root in the United States in 1932, presidential candidate Franklin Roosevelt (A Democrat) was able to defeat Herbert Hoover (a more liberal Republican) by promising the New Deal, a Stimulus Package that would address the wreckage caused by the Depression.
The leftists continue for the next 40 years through world war II, social welfare programs were expanded, and until the late 1970s that there began to be backlashes and there was a return to liberalism.
Conclusion
As can deduce from their history, the liberals and the leftists quite have dissimilar ideologies.
Hence, there is always a clash, while the liberals are more overbearing and support the upper classes, the leftists on the other hand are more people-centric and made a less harsh policy.