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Input: But as Sen. Blanche Lincoln proved by winning the bruising Democratic primary runoff  Democrats do not necessarily serve at the pleasure of the party's left flank. Lincoln survived a massive and unprecedented mobilization by labor unions and liberal advocacy groups in Arkansas  raising questions anew about the political power of the progressive movement.
 Labor alone spent some $10 million on the race  airing an onslaught of advertisements assailing Lincoln for her connections with corporate interests  and had hundreds of paid workers in the state canvassing on behalf of her runoff opponent  Lt. Gov. Bill Halter. High-level union organizers poured into the state in the closing days of the campaign  feeding facts and figures to reporters to tout the likelihood of Lincoln's defeat _ a victory they were convinced was theirs.
 Lincoln's win stunned labor and progressive leaders. But regardless  they said every penny spent to support Halter was worth it. Forcing Lincoln into a race for survival  they said  demonstrated to other moderate Democrats in the country that support from the party's liberal base cannot be taken for granted.
 Steve Rosenthal  a veteran labor organizer who was a key strategist in the campaign against Lincoln  said forcing her into a runoff and having Halter come within four percentage points of her on Tuesday was "a phenomenal victory."
 "There are other senators sitting on Capitol Hill saying  `I don't want to go through what Senator Lincoln went through ' and that's the important lesson " Rosenthal said. "The labor movement is about protecting rights and expanding rights for workers. As long as the labor movement is seen as spending its resources only to protect Democrats  it loses."
 It was an audacious move for labor to take on a sitting senator in a conservative right-to-work state that gave rise to Wal-Mart and where labor unions have long been weak. But the labor movement was bullish  believing Lincoln to be vulnerable. In Halter  an ambitious politician who had long eyed higher office  the movement believed it had found the right vessel with which to sink Lincoln.

New Questions About Progressives' Power