The conviction of I. Lewis Libby Jr., who served as chief of staff to Vice President Cheney, on felony obstruction-of-justice, perjury, and false statement charges is putting President Bush on the political spot, as he faces both increasing demands to pardon the ex-staffer and warnings that such a pardon would be a serious mistake.

The White House moved quickly yesterday to dismiss all talk of clemency as rash and premature.

“I’m aware of no such request for a pardon. And as is afforded to all Americans, there is a process that is followed in which to apply for a pardon,” a White House spokeswoman, Dana Perino, said at a news briefing for reporters. “I don’t think that speculating on a wildly hypothetical situation at this time is appropriate.”

Appropriate or not, the prospect of a Libby pardon is quickly becoming a political football. Prominent Democrats, while urging Mr. Bush not to consider clemency for Libby, asserted that the verdicts amounted to a broad judgment on the conduct of the White House as a whole.

“It’s about time someone in the Bush Administration has been held accountable for the campaign to manipulate intelligence and discredit war critics,” Senate Majority Leader Reid said in a statement moments after the verdicts were returned. “Now, President Bush must pledge not to pardon Libby for his criminal conduct.”

The chairman of the Democratic National Committee, Howard Dean, echoed that sentiment, as did one of the candidates for the party’s presidential nomination in 2008, John Edwards. “This is a situation where he has been convicted as part of a crime committed as part of his official responsibilities in working for the vice president. He absolutely should not be pardoned,” Mr. Edwards told MSNBC.

Calls for a Libby pardon came yesterday primarily from the defendant’s friends, as well as his allies in the conservative press.

“I’m sure there’s going to be a lot of pressure on the White House to do this,” a lawyer and former Justice Department official friendly to the defense, Victoria Toensing, said. “At a certain point, enough is enough.”

A pivotal question for the White House now is whether Libby is permitted to remain free while he appeals his convictions. If the trial judge or the appeals court grants the former staffer bail pending appeal, Mr. Bush will be free to defer a decision on a pardon until after the appeal is resolved, probably sometime next year. That would be close to the end of Mr. Bush’s term, which could make a pardon more politically palatable. If Libby is ordered to report to jail soon after his sentencing, which will likely take place in the summer or fall, pressure on Mr. Bush’s to act to stave off any prison sentence could be intense.

President Bush and Vice President Cheney gave some indication yesterday of their concern. According to Ms. Perino, Mr. Bush watched television coverage of the verdicts and said he respected the jury’s decision, but was sad for Libby and his family.

Mr. Cheney said in a statement that he was “very disappointed with the verdict.” He also praised Libby’s service to the nation.

Libby’s lead defense attorney, Theodore Wells Jr., also said he was “very disappointed” with the outcome. He said he would move for a new trial and, failing that, appeal. “We have every confidence that, ultimately, Mr. Libby will be vindicated,” he said.

The special prosecutor for the case, Patrick Fitzgerald, said he was “gratified” by the jury’s verdict. “It’s sad that we had a situation where a high level official, a person who worked in the Office of the Vice President, obstructed justice and lied under oath. We wish that that had not happened, but it did,” the prosecutor said.

After 10 days of deliberations, jurors convicted Libby yesterday on one count of obstruction of justice, one count of making false statements to the FBI, and two counts of perjury. He was acquitted on one count of making false statements. The charges stemmed from an investigation into the disclosure of the identity of a CIA operative, Valerie Plame, in a syndicated newspaper column discussing criticism her husband, Joseph Wilson IV, leveled at Messrs. Bush and Cheney over White House statements about Iraq’s nuclear efforts. Libby was the only person charged in the probe. No one was ever charged with the leak, which originated with a State Department official, Richard Armitage.

The only juror to speak publicly after the verdict, Denis Collins, said jurors wondered why Libby was in the dock alone. “It was said a number of times, ‘What are we doing with this guy here? Where’s Rove? Where are these other guys?’ We’re not saying that we don’t think Mr. Libby was guilty of the things we found him guilty of but that it seemed like…he was the fall guy, ” Mr. Collins, an author of books on espionage, Enron and other subjects, said. “Some jurors commented at some point, ‘I wish we weren’t judging Libby … this sucks.'”

Mr. Fitzgerald said Libby’s story that he thought he learned about Ms. Plame from an NBC journalist, Timothy Russert, was so starkly at odds with the recollection of Mr. Russert and others that it had to be pursued. “To me, it’s inconceivable that any responsible prosecutor would walk away from the facts we saw in December 2003 and say, ‘There’s nothing here. Move along folks,'” the prosecutor said.

Estimates of the sentence recommended by federal guidelines ranged from 15 months to ten years. “There is a heck of a lot of play in the joints,” a law professor at Ohio State University, Douglas Berman, said. He said some jail time was all but certain. “I can’t think of a single case where a defendant went to trial and lost and didn’t fess up, having guidelines in the incarceration range, not getting incarceration.”

While the White House seemed to be directing attention to the Justice Department’s office which handles clemency requests, its rules do not permit pardon applications from criminals who have not completed their prison term. “This is not a case that would ordinarily be eligible to apply for a pardon,” a former head of that office, Margaret Love, said. “It’s unclear how the traditional grounds for a pardon would apply,” Ms. Love said. Action could also be complicated by the decision of Justice Department officials to recuse themselves from the prosecution.

Mr. Bush has clear authority to issue a pardon without a Justice Department recommendation, over the department’s objection, or even without a formal request from Libby. There is ample precedent for that. On Christmas Eve 1992, President George H.W. Bush pardoned six men caught up in the Iran-Contra scandal. A former defense secretary, Caspar Weinberger, was pardoned before being brought to trial. As President Clinton left office in 2001, he pardoned a fugitive billionaire, Marc Rich, over the objections of some prosecutors. Libby, who was then an attorney in private practice, helped Mr. Rich prepare his pardon request.

The furor that erupted over that pardon may explain why a statement from Mrs. Clinton yesterday expressed general approval of the verdict, but avoided any discussion of clemency. “While justice has been served in the Libby case, the real lesson to come from it is that we must be vigilant in ensuring that the intelligence on burgeoning threats to our nation is beyond reproach,” Mrs. Clinton said.

Perhaps in an indication of Mr. Bush’s low approval ratings, Congressional Republicans remained conspicuously quiet yesterday about Libby’s convictions and the possibility of a pardon.

Still, since many conservatives assert that the prosecution was a miscarriage of justice, it seems plausible that some Republican presidential candidate might try to appeal to that constituency by endorsing a pardon. None of the top Republican contenders jumped at the chance yesterday.

A former governor of Massachusetts, Mitt Romney, would seem the most likely prospect to take such a stance. His campaign has close ties to several of those involved in Libby’s defense. A spokesman for Mr. Romney, Kevin Madden, did not respond to requests for comment for this article. The campaigns of Senator McCain of Arizona and Mayor Giuliani also remained silent yesterday. Mr. McCain has been highly critical of Mr. Cheney and might be unlikely to come to the defense of one of the vice president’s aides. Mr. Giuliani ran the U.S. Attorney’s office in Manhattan when Mr. Fitzgerald was hired there.