Some form of the Employee Free Choice Act (EFCA) might have received a key boost Friday from Sen. Arlen Specter (D-Pa.), saying he would support cloture for the controversial labor bill.

In a reversal of his previous position, Specter told a panel discussion at the "Netroots Nation" liberal bloggers' convention that he would support a procedural vote to bypass a filibuster for a modified version of the "card check" legislation.

"I expect the cloture vote to occur on a modified version of the Employee's Free Choice legislation," Specter told the bloggers. "And I will support that cloture vote."

Specter, a key centrist senator whose vote is critical to the success of EFCA, announced in late March that he would oppose the bill in its current form, as well as cloture for the legislation.

The statement, while a boon for labor organizing legislation, is far from definitive to the extent that it is unclear what a "modified" version of EFCA would resemble.

After switching parties to pursue reelection as a Democrat, Specter had maintained that his position on "card check" would remain consistent.

But the veteran senator has been under pressure from a primary challenge by Rep. Joe Sestak (D-Pa.) in which polls have found Specter flagging.

Business interests had seen EFCA's prospects wane in recent months, as a variety of centrist Democrats have expressed skepticism about some of the bill's key components.

And while Specter did not tip his hand as to his final vote on the bill overall, his opposition to a filibuster would allow for the bill's passage with a lower, 50-vote threshold.

"Senator Specter owes Pennsylvanians an explanation on where he stands on the [EFCA]." said Katie Packer, executive director of the Workforce Fairness Institute.