This entry is a work in progress; updated/reviewed 5/22/2016; suggestions welcome -- please email email@example.com
George Creel, Chairman of the Committee on Public Information -- the first USG propaganda agency (1917-19) -- had, before he assumed that position (thanks in large part of his loyal support of Woodrow Wilson), became something of a passé muckraker by the second half of the 1910s. This may have contributed to his willingness to work for the USG (since his earliest years Creel, born poor, had always been looking for a job; in his mid-teens, he ran away from his Missouri home and worked at country fairs, doubtless a good "real life" preparation of propaganda tsar for that "generalissimo" of the art, the president himself); the president was thus labeled by Harold D. Lasswell in his groundbreaking volume, Propaganda Technique during the World War (1927): 216-217.
Here is an interesting passage on muckraking from James Rorty, "Yesterday's Muckrakers," The Nation, Volume 149, Issue 24 (December 9, 1939): 654:
[S]tarting in 1901 and 1902, with priority disputed among Lincoln Steffens [he hired Lippmann for a brief period in 1904 during the latter's early socialist tendencies, which definitely ended when Walter left the Socialist party during WWI], Mark Sullivan [he wrote about Creel], and Ray Standard Baker, and among McClure's, Collier's Weekly [to which Creel contributed], and the Atlantic Monthly as publishing mediums, the muckraking movement spread like a forest fire and was soon devouring three-quarters of the wood pulp that went into the magazines. By 1910 a dozen muckraking periodicals, each with a score of lesser sheets competing in the the same market. But by 1916 there was nothing left except a pulp paper Pearson's [to which Creel contributed], rapidly expiring in the hands of the raffish Frank Harris. Big business dispatched the muckraking magazines either by cutting off their credit or by "joining" them through the business office; the muckrakers found themselves without a market, and the war completed their demoralization.
Some of the muckrakers, like Charles Edward Russell, Upton Sinclair [acquainted with Creel; they became political/ideological enemies; Sinclair defeated Creel for the California Democratic gubernatorial nomination in 1934], Albert Bullard [also known to Creel and considered by Vaughn to be a key intellectual figure in the origins of the Committee on Public Information, for whose Foreign Section he eventually worked (in Russia)], and George Creel (who else), were Socialists [Creel however denied he was a Socialist when so asked by Congress during his tenure as Chairman of the CPI], Ray Stannard Baker, Samuel Hopkins Adams, Ida Tarbell, Will and Wallace Irwin [Will was chief of the CPI foreign department in 1918] Ernest Poole [also a CPI-er], Harvey O'Higgins [a associate chairman of the CPI who wrote a profile on Creel in the New Yorker in a 1925 that I haven't been able to obtain, as well published a book, Some Distinguished Americans (1922), in which Creel is not mentioned] -- into the propaganda apparatus for the war. ...
The muckrakers of the nineteen hundreds acquired a big following, accomplished many reforms, and at their peak were dressed up with a good deal of power. But they didn't where to go or what to do do; so it was Heigh-ho, heigh-ho, it's off to war we go. Today  it would seem that candidates ... for chairman of the Committee on Public Information (George Creel) are already almost visibly standing in line.