Sam Brownback, R-Kansas, an ardent opponent of embryonic stem cell research, promised to filibuster the spending bill until Specter dropped the broader stem cell language.

CNN: Senators defer fight on stem cell research

John Cornyn, R-Texas, chairman of the National Republican Senatorial Committee, has said GOP members would filibuster any attempt by Democratic leaders to seat Franken early, even if he remains in the lead, until the certificate is signed.

CNN: Tense moments in Minnesota Senate recount

But even before the hurricane, Senate Finance Committee Chairman Charles Grassley (R-Iowa) had publicly conceded Republicans didn't have the 60 votes needed to overcome a filibuster of the measure.

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