It's very hard to find this essay/op-ed Whitman wrote because it's not included in Leaves of Grass and Google keyword searches always prioritize sites which discuss Leaves of Grass. Whitman wrote an article for the newspaper in which he railed against politicians in general but singled out Lincoln as an exception. It is a very long essay, probably 5000 words and some of its passages are just as good as anything in Leaves of Grass. There are long lists of creative insults for politicians in the essay and he often likens them to jigolos and prostitutes. I know that one of the sentences has the structure: from the x, from the y, they come, where x and y are usually some seedy place. The central thesis of the essay is that all politicians til now have been bad, except Lincoln.
It's "The Eighteenth Presidency!", found here.
Whence then do these nominating dictators of America year after year start out?
From lawyers' offices, secret lodges, back-yards, bedhouses, and bar-rooms; from out of the custom-houses, marshals' offices, post-offices, and gambling hells; from the President's house, the jail, the venereal hospital, the station-house; from unnamed by-places where devilish disunion is hatched at midnight; from political hearses, and from the coffins inside, and from the shrouds inside of the coffins; from the tumors and abscesses of the land; from the skeletons and skulls in the vaults of the federal almshouses; from the running sores of the great cities; thence to the national, state, city, and district nominating conventions of These States, come the most numerous and controlling delegates.
Who are they personally?
Office-holders, office-seekers, robbers, pimps, exclusives, malignants, conspirators, murderers, fancy-men, post-masters, custom-house clerks, contractors, kept-editors, spaniels well-trained to carry and fetch, jobbers, infidels, disunionists, terrorists, mail-riflers, slave-catchers, pushers of slavery, creatures of the President, creatures of would-be Presidents, spies, blowers, electioneerers, body-snatchers, bawlers, bribers, compromisers, runaways, lobbyers, sponges, ruined sports, expelled gamblers, policy backers, monte-dealers, duelists, carriers of concealed weapons, blind men, deaf men, pimpled men, scarred inside with the vile disorder, gaudy outside with gold chains made from the people's money and harlot's money twisted together; crawling, serpentine men, the lousy combings and born freedom sellers of the earth.