Part of a $53 million effort, the mobilization is aimed hitting union members who may feel unfamiliar with Obama, a U.S. senator from Illinois who will presumably receive the Democratic nomination this week. Michigan, Ohio, Wisconsin and Pennsylvania are the first of what will eventually be 24 "priority" states receiving AFL-CIO attention, The Hill, a Washington publication, reported Monday.

"This is the biggest grassroots effort in history," Karen Ackerman, political director of the AFL-CIO, told The Hill. "(The mail piece) will hit mail boxes this week as Obama accepts the nomination."

The glossy mailer describes Obama as a working-class champion who learned from his mother and grandparents to appreciate hard work and that he passed up Wall Street jobs to work in Chicago neighborhoods hurt by steel mills closure. By contrast, Republican presidential candidate John McCain is cast as an out-of-touch owner of 10 homes, who uses a $12.6 million corporate jet and wears $520 Italian shoes.