Sen. Ted Stevens, R-Alaska, recently convicted on federal corruption charges, has not ruled out asking the president for a pardon.
Neither Libby nor Stevens has filed a formal application with the Department of Justice.
Because the Justice Department process is so complex, often offenders will attempt to find surrogates to circumvent the process all together and make a direct plea to the president.
For example, on Monday Sen. Dick Durbin, D-Ill., wrote a letter asking the president to commute the sentence of Ryan, the former Illinois governor, who is serving a 6½-year term in federal prison.
Durbin told reporters that he was not asking for a pardon of the 74-year-old Ryan, saying, "no one can or should excuse his official misconduct," but a commutation of his sentence, which would allow him to leave prison and return to his ailing wife.
Rep. Dana Rohrabacher, R-Calif., among other congressmen, has publicly urged the president to commute the sentences of two former Border Patrol agents who were convicted of shooting a drug smuggler who was attempting to enter the United States. The men, Jose Compean and Ignacio Ramos, are currently serving sentences in excess of a decade.
In a statement, Rohrabacher criticized the president for failing to include Compean and Ramos in his most recent round of pardons and commutations.
"The fact that the president has neglected to free these men from their imprisonment while freeing drug dealers, embezzlers and other criminals is insulting to the American people who have been begging and pleading for the president to release the agents whose prosecution was unjust from the beginning."
Critics charge that the pardon process at the Department of Justice has become overwhelmed with requests and is unable to sufficiently tackle each one.
"The pardon program at DOJ has been in disarray a long time," says George Lardner from the Center of the Presidency, who is writing a book about presidential pardons.
"Going through channels at the Department of Justice often is creating a place where your application goes to die," says Doug Berman, a law professor at Ohio State's Moritz College of Law who has written extensively on the pardon issue and currently is representing clients attempting to get clemency from President Bush.
He believes that the Department of Justice is wrong to try to regulate the pardon process as much as it does. "The creation of formalized regulations sends a signal, 'hey unless you jump through these hoops you don't get to play the game.' It is neither justified nor in keeping with the framer's vision of giving the president sole power."
"In President Clinton's day, they short-circuited the process because Clinton was exasperated by the DOJ arduous process to submit applications," says Lardner.
But Clinton's effort to bypass the pardon process at Justice landed him in some trouble on the last day of his presidency when he pardoned financial fugitive Marc Rich, who had fled the country to avoid tax evasion charges. Rich's ex-wife had donated substantial amounts of money to the Clinton Library and some Republicans suggested that Clinton had pardoned Rich as a kind of "quid pro quo" for those contributions.
After the controversy prompted heated congressional hearings, Clinton wrote an op-ed in The New York times calling the suggestion "utterly false." He wrote, "There was absolutely no quid pro quo. Indeed, other friends and financial supporters sought pardons in cases which, after careful consideration based on the information available to me, I determined I could not grant."
Some believe that Bush might consider a pre-emptive pardon for some current and former officials who have yet to be charged with a crime.
"The preemptive pardon has been used in history," says Lardner, "but if Bush sticks to his pasty stingy approach to pardons, he won't do it."
The White House refused to comment on the issue.
But speculation over those who might be pardoned includes former Attorney General Alberto Gonzales for his role in firing several U.S. attorneys in 2006.
Gonzales resigned after months of criticism that the prosecutors had been terminated because of improper political considerations. Attorney General Michael Mukasey has appointed a career prosecutor, Nora Dannehy, to conduct further investigation into the matter.
George Terwilliger, a lawyer for Gonzales, released a statement saying, "There is no basis to even suggest that a pardon is needed for anything. What is needed is for the Justice department to bring those matters to a rapid close because doing otherwise would be unconscionable continuation of a fully and publicly reported investigation that showed no wrongdoing by the former Attorney General whatsoever. It is time for this to end."