In his Senate farewell speech dubbed “a closing argument to a jury of my colleagues,” Sen. Arlen Specter on Tuesday accused the Supreme Court of overreaching and extremists of reshaping the nation’s political system.

“Congress should act to try to stop the Supreme Court from further eroding the constitutional mandate of separation of power,” Specter said on the Senate floor. “The court has been eating Congress’ lunch by invalidating legislation with judicial activism after nominees commit under oath in confirmation proceedings to respect Congressional fact-finding and precedents.”

Specter lost the Pennsylvania Democratic primary — and his bid for another term — to Joe Sestak in May. Specter had been a Republican for three decades, but he switched parties in April 2009 to strengthen his odds at re-election. Former GOP Rep. Pat Toomey ultimately won the Senate seat.

As Specter said goodbye on the Senate floor, he trained his criticism at Chief Justice John Roberts and Justice Samuel Alito, both of whom he voted to confirm, for casting deciding votes in the Citizens United campaign finance reform case. Specter formerly served as chairman of the Judiciary Committee.

“Chief Justice Roberts and Justice Alito repudiated their confirmation testimony and provided the key votes to permit corporations and unions to secretly pay for political advertising — effectively undermining the basic democratic principle of the power of one person/one vote,” Specter said.

But Specter didn’t just criticize the courts; he also chastised Congress, and specifically Republicans, for not passing legislation to undo the decision and require greater disclosure of corporate campaign spending. He used the example to demonstrate how partisanship has increased on Capitol Hill.

“Senior Republican Senators have recently abandoned long-held positions out of fear of losing their seats over a single vote or because of party discipline,” Specter complained. “With 59 votes for cloture on the Democratic side of the aisle, not a single Republican would provide the 60th vote to advance legislation on key issues such as identifying campaign contributors.”

Specter also remarked on the current political climate, which he said is too heavily influenced by “extremists.” He said it is the current landscape that led to his downfall, as well as those of other longtime Members like GOP Sen. Bob Bennett (Utah) and Rep Mike Castle (Del.). Specter also criticized those extremists for forcing Sen. Lisa Murkowski to run a write-in campaign after losing the GOP primary to tea-party-backed Joe Miller. Party officials backing extreme candidates over moderate incumbents “is a form of sophisticated cannibalism,” Specter argued.

“The spectacular re-election of Sen. Lisa Murkowski on a write-in vote in the Alaskan general election and the defeat of other tea party candidates in 2010 in general elections may show the way to counter right-wing extremists,” Specter said. “Her victory proves that America still wants to be and can be governed by the center.”

Just a handful of other Republicans sat in the chamber during Specter’s address — one of the more fiery of the farewells — but some of the Pennsylvanian’s closest allies were in attendance including Judiciary Chairman Patrick Leahy (D-Vt.) and Majority Leader Harry Reid (D-Nev.).