The AFL-CIO said Wednesday that it would wage a "very aggressive" campaign in the runoff election between Sen. Blanche Lincoln (D-Ark.) and her Democratic primary challenger.

The labor group said it would spend what it needs to in order to help Arkansas Lt. Gov. Bill Halter unseat Lincoln in a Democratic primary challenge.

"We're in it to win it," AFL-CIO political director Karen Ackerman said in a conference call Wednesday. "We are certainly ready and able to spend whatever we need to do on behalf of Halter."

The union said it saw a "real victory for working people" in last night's Arkansas primary, in which neither Lincoln nor Halter received 50 percent of the vote, forcing a June 8 runoff primary between the two.

The AFL-CIO and other labor groups poured millions into the race on Halter's behalf, angered by Lincoln's stance on healthcare reform legislation and a union organizing bill, among other issues.

Ackerman also hailed the victory for Democrats in Pennsylvania's 12th congressional district, and downplayed incumbent Sen. Arlen Specter's (D-Pa.) loss in a Democratic primary. She said that local AFL-CIO officials had decided to back Specter, in part due to their years of support for him.

But she said that their focus had shifted to Arkansas, where they will commit resources to Halter, though Ackerman wouldn't put a price tag on the amount.

"We figure that it is very important to take a stand against incumbents or candidates who are not sympathetic to the needs of working people, and who have not really proven themselves to fight for the economic security of working people," she said.

Cross-posted from the Briefing Room.