[1][2] Called "a demagogue of extraordinary power,"[3] he frequently gave long and caustic speeches that focused on four general topics: contempt for the press, for capitalists, for politicians, and for Chinese immigrants.

As part of this effort he helped to start a loosely organized association of laborers, which within a year's time grew into the Workingmen's Party of California.

For several years the Workingmen's Party would provide a forum for Kearney to speak before growing crowds of unemployed people in San Francisco.

He thought of himself as a "workingman's advocate",[10] although he remained highly critical of unions throughout his life and frequently denounced strikes.

Middle class critics, fearful of Kearney's radical rhetoric and pledges, questioned whether Irish immigrants—embodied by Kearney—should have the right to dictate social policy in San Francisco.

As The Argonaut, the newspaper founded and published by the former Attorney General of California, Frank Pixley, noted: When an organization, composed almost entirely of aliens, who are themselves here by the sufferance of a generous hospitality, band themselves together in defiance of the law to drive out a class, who, however objectionable, have the same legal rights as themselves, it is an act of insolent audacity that ought to move the indignation of every honest man.

At an outdoor gathering place near San Francisco City Hall known as "The Sandlot" he regularly spoke in front of crowds that numbered as many as 2,000 people.

[10] Observers said he had a natural ability to stir up crowds, and since his speeches often lasted as long as two hours he had plenty of opportunity to incite the audience.

One of his trademarks was to gradually increase the volume of his speech until it reached fever pitch, then dramatically throw off his coat and unbutton his collar.

He attended a club in San Francisco known as the Lyceum of Self-Culture, where he sharpened his speaking skills at weekly forums.

"[24] Kearney faded from the public's eye by the early 1880s, leaving as his legacy only the anti-Chinese laws that the Workingmen's Party had passed at the 1879 California Constitutional Convention.

Many of these laws, which included a ban on the employment of Chinese laborers, were ruled unconstitutional by the federal Ninth Circuit Court.

[25] Today there is a Kearny Street in San Francisco that runs through Chinatown; however it was not named after Denis Kearney but after the Mexican–American War Army officer Stephen W.