U.S. Sen. Arlen Specter, R-Pa., announced his bid for re-election Friday morning in State College, saying his top priority would be protecting Pennsylvanians from terrorism.

About 75 supporters and friends joined Specter in the Senate Suite of the Penn Stater Conference Center Hotel to make the announcement. U.S. Sen. Rick Santorum, R-Pa., U.S. Rep. John Peterson, R-Pa., State Sen. Jake Corman, R-Bellefonte, Specter's wife Joan, and two of his granddaughters accompanied Specter as part of a tour throughout Pennsylvania announcing his campaign.

Specter is the only incumbent U.S. senator in the country facing a primary challenger this election. U.S. Rep. Pat Toomey, R-Pa., is competing with Specter for the Republican nomination to the U.S. Senate race, while U.S. Rep. Joe Hoefel, D-Pa., will challenge the winner of the Republican primary in the November general election.

If re-elected, Specter would be the first U.S. senator in Pennsylvania history to be elected to five consecutive terms.

Specter said that by passing legislation to strengthen the Homeland Security Act, agencies such as the CIA and FBI would be better able to share intelligence information. He advocated making Homeland Security Secretary Tom Ridge responsible for the pooling of this information.

"If we had put all the dots together we could have prevented 9/11. I say that from my position in the intelligence community," Specter said.

Economic development and education were the two other priorities Specter said he was concerned with. He voiced support for tariffs on international steel, adding that a strong steel industry was important to national defense.

While discussing his education agenda, Specter spoke fondly of Penn State.

"I am proud of Penn State. I am proud of [Joe Paterno] and I am proud of a community synonymous with winning," Specter said.

U.S. Sen. Rick Santorum said Specter played a crucial role in bringing education funding for Pennsylvania.

"It's inconceivable to [not re-elect] someone who has done so much. I stand here and say that Pennsylvania has needed Arlen Specter and he has been there for her," Santorum said.

Toomey, a three-term member of the U.S. House of Representatives, has criticized Specter for siding with Democrats to raise taxes and bloat the deficit with expensive Pennsylvania projects.

The Associated Press contributed to this report.