Explanation: In the presidential election of 1948, facing stagnant poll numbers and a seemingly unpopular incumbency, Democrat US President Harry Truman - who had taken over from FDR, who had died in office during WW2 - chose a radical and unusual route. Instead of becoming more moderate to sway voters who had defected to the Republican Party, Truman chose to throw caution to the wind and make the core Democrat platform of 1948 on unapologetic liberal progressive values.

… at the time, the “Dixiecrat” wing of the Democrats was still strong, and very much opposed to progressive ideas on racial equality. Strom Thurmond, one-such Dixiecrat, defected from the Democratic Party and ran as a third-party candidate in favor of segregation. Not only that, but from the opposite wing of the Democratic Party, Henry Wallace split from the Democrats to run as a Progressive Party candidate, denouncing Truman as not left-wing enough.

Things actually looked pretty dicey during the 1948 election, with polling being quite negative on Truman’s chances. However, Truman remained confident of victory - sometimes said to be the only person in his campaign team who was confident of victory! Sure enough, when election day rolled around, Truman won by a pretty comfortable margin, shocking many. Thurmond and Wallace would each receive around 2.5% of the popular vote, while the Republican candidate won ~45%, and Truman won 49.5% - a near-majority!

Truman was a farm boy himself, had a pretty good idea of the opinions of rural America - who, at the time, were still lacking in many amenities like phone access, which would have allowed them to be polled. The then-progressive rural vote, thus, pulled through for Truman and allowed him a stunning victory which he used to push through parts of his "Fair Deal" which could be forced through the still-moderately-conservative Dem-controlled Congress.

“The people don’t want a phony Democrat. If it’s a choice between a genuine Republican, and a Republican in Democratic clothing, the people will choose the genuine article, every time; that is, they will take a Republican before they will a phony Democrat, and I don’t want any phony Democratic candidates in this campaign.” - Truman