Republicans will lose the Pennsylvania Senate seat if Republican candidate Pat ToomeyPatrick (Pat) Joseph ToomeyNewly declassified memos detail extent of improper Obama-era NSA spying Overnight Tech: FCC won't fine Colbert over Trump joke | Trump budget slashes science funding | Net neutrality comment period opens Appeals court decision keeps lawsuit against NSA surveillance alive MORE wins his primary against Sen. Arlen Specter next year, Specter warned Thursday.

Specter threatened that his defeat would lead directly to the passage of the Employee Free Choice Act (EFCA, or "card check"), as well as increased taxes and spending.

"If Toomey is the Republican nominee, we lose the seat in the fall," Specter said during a Thursday afternoon press conference in Pennsylvania. "If he’s the nominee we lose the seat and you have card check, and you have tax increases and you have all of the big Obama spending programs."

Specter acknowledged his more aggressive tack toward Toomey this cycle, compared to his slow response out of the gate in his 2004 faceoff against Toomey.

"This time we won’t be ambushed," Specter said. "So Fasten your seat belts fellows."