Your search within this document for 'plug' resulted in two matching pages.
1

“... packed the convention with a lot of plug-ugly delegates, many of them representing purely fictitious locals, and had refused to seat properly accredited delegates from bona fide organizations, amongst these De Leon himself. This element, once it found itself in control, promptly Un- did the work of the 1905 convention; the political clause of the preamble, or declaration of principles, was eliminated and the organization placed squarely upon a physical force basis. Sub- sequent history has demonstrated, amply and convincingly, the logical and inevitable consequences that flow from assuming such a posture; the Anarchists did what they are always fated to do, furnish the raison detre for the police spy, demoralize the working class and discredit the very name of Labor. The career of the I. W. W. since 1908, most of this time under the leadership of Haywood, furnishes a striking lesson of what not to do, a lesson that should not be lost sight of by any^ thinking workingman...”
2

“... vote, that there was no Socialist ticket in the field, that De Leon had been expelled from the party, and that he was a union wrecker. Tammany held the same language. Feverish Work to Beat De Leon The scum of the great metropolis was let loose in the 16th; so great was the fear that De Leon would carry the district that open-air meetings of the Socialist Labor Party were broken up by the police. Big Chief Devery, then head of the whole police department of New York city, sardonically answered the Sections protest with the reply that the meet- ings of the Socialist Labor Party were interfered with because the Democratic Party had applied to hold meetings on the very same corners a long time ahead of the Socialist Labor Party. On the day of election I saw a Socialist Labor Party chal- lenger at the polls slugged by plug-uglies, such as are not seen by daylight at any other time of the year, but who make their appearance on election day and who appeared in profusion in...”