When you ask this sort of question, it's always better to include more of the context than you have done here. You have not even given the whole sentence.
However, "aw-shucks folksiness" is undoubtedly an American expression. The term "aw-shucks" has many meanings, ranging from an expression of shyness [Mary-Lou to Billy-Jo: "I really like you". Billy-Jo: "Aw shucks, Ma'am".] to one of surprise and/or despair [7th Cavalry Scout: "Injuns, General - thousands of them!" General Custer: "Aw, shucks!"] Whatever the circumstances, it always signifies that the speaker is a homely, unsophisticated, salt-of-the-earth individual: a cowboy, a hill-billy, a farmer. In other words, a man of the people - which is what "folksiness" also means, You would have expected to hear it from President Lincoln, but probably not from President Nixon....
Apologies to any North Americans for my take on your culture...