Apparently the name for these non-union picketers is "hired feet" and Barry Obama has promised to be one if elected President, as Taranto explains:
http://www.opinionjournal.com/best/

"TownHall.com reports on a preposterous promise Obama made over the weekend to a union convention:

"I stood on the picket line and marched with workers at the Congress Hotel in Chicago last week," Obama said. "I had marched with them four years earlier and I told them when I left that if they were still fighting four years from now, I'd be back on that picket line as president of the United States and we'll get the Congress Hotel organized.

It wouldn't be the first case in which a picket line was manned by people who don't belong to the union. The Washington Post reports on another such example:"
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[snipped discussion of fake picketers]

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Although their placards identify the picketers as being with the Mid-Atlantic Regional Council of Carpenters, they are not union members.

They're hired feet, or, as the union calls them, temporary workers, paid $8 an hour to picket. Many were recruited from homeless shelters or transitional houses.

So Obama is promising that as president he will serve as a hired foot--a job a street vagrant can do. Does he have the foggiest clue what the president actually does?"