Two Republican senators planned to introduce a resolution Tuesday calling for a special counsel in the security leak investigation, as Attorney General Eric Holder continued to defend his decision to appoint two lawyers from within his department to handle the politically sensitive probe. 

Sens. John McCain, R-Ariz., and Lindsey Graham, R-S.C., were unveiling the measure on the Senate floor, claiming the U.S. attorneys appointed by Holder do not have the necessary professional distance to probe Obama administration leaks. 

McCain is also standing by his assertion that the leaks were politically motivated, a charge the White House strongly denies. 

The resolution is sure to divide lawmakers, despite a growing sense of bipartisan outrage over the leaks themselves. 

Sen. Dianne Feinstein, D-Calif., chairwoman of the Senate Intelligence Committee, said Tuesday that she would oppose the resolution -- defending the professionalism and independence of the attorneys Holder selected. 

Holder, testifying Tuesday morning before the Senate Judiciary Committee, also said the attorneys he assigned to the leak case are up to the job. 

"These U.S. attorneys are fully authorized to consult with members of the intelligence community, to follow all appropriate leads wherever they do lead, and ultimately to prosecute any criminal violations to the fullest extent of the law," he said. "They will do an independent and thorough job." 

Holder said unauthorized leaks of classified information could jeopardize security and "will not be tolerated." Holder said the allegations "are of great concern to me personally." 

Recent leaks have contributed to several recent news stories about secretive programs, including two New York Times stories -- one on President Obama's involvement in shaping the list of terror targets from U.S.-led drone strikes, the other on the cyber-campaign to disrupt Iran's nuclear program. 

The leaks, and the subsequent investigation announcement, have prompted a political firestorm on Capitol Hill. Republicans have charged that top officials in the Obama administration cleared the leaks in order to furnish information to reporters that would help make the president look strong in an election year. 

"It was obvious from reading the stories that the administration is trying to give the president glory," Rep. Peter King, R-N.Y., chairman of the House Homeland Security Committee, told Fox News on Monday. 

White House Press Secretary Jay Carney called that idea "wrong and absurd." 

Ahead of Holder's testimony Tuesday, Sen. Charles Grassley, R-Iowa, challenged the attorney general on his assigning of "political appointees" to the case. He, too, called for an independent special prosecutor. 

"Despite attempts to package this as a special prosecutor, the attorney general's decision treats the grave national security matter like a regular criminal investigation," Grassley said. 

Sen. Patrick Leahy, D-Vt., though, supported Holder's decision, describing the investigators as "tough, honest prosecutors." 

Holder said he has "great faith" in them, and said he's charged them to follow leads wherever they go, even into the Executive Branch.