The State Department has a message for White House candidates wanting to expound on sensitive diplomatic issues: Shut up.

Traditionally silent during presidential campaigns filled with divisive foreign policy debates, the department on Friday delivered a rebuke to would-be nominees of both parties whose recent comments have complicated U.S. efforts to overcome deep suspicion about the war on terrorism in the Muslim world.

"Those who wish to hold office can speak for themselves and whoever is elected in 2008 and comes into office in 2009 will then be in a position to talk about what they intend or plan to do," said deputy spokesman Tom Casey, a career foreign service officer.

First it was Barack Obama's talk of dialogue with dictators and invading Pakistan to kill Islamist militants, then it was Hillary Rodham Clinton refusing to rule out the use of nuclear weapons to that end. Now, the Democratic front-runners have been joined by radical Republican Rep. Tom Tancredo, who threatened to bomb Muslim holy sites to stop terror attacks.

The State Department had hoped to steer clear of controversy, complaints and public protests sparked by Obama and Clinton, but Tancredo's comments bumped up against the limit of diplomatic patience.

Casey had unusually harsh words for Tancredo, R-Colo., who said this week that if elected he would threaten to bomb the Saudi cities of Mecca and Medina, Islam's two holiest sites, to deter attacks on the United States.

"It is absolutely outrageous and reprehensible for anyone to suggest attacks on holy sites, whether they are Muslim, Christian, Jewish or those of any other religion," a clearly agitated Casey told reporters, shaking his head in disgust.

"To somehow suggest that an appropriate response to terrorism would be to attack sites that are holy and sacred to more than a billion people throughout the world is just absolutely crazy," he said, denouncing "any suggestion that the defense of the American homeland or the defense of American interests would ever justify attacking holy sites."

Tancredo's suggestion to bomb Mecca and Medina came as Secretary of State Condoleezza Rice and Defense Secretary Robert Gates were on a sensitive mission to the Middle East that included a stop in Saudi Arabia.

Tancredo told about 30 people at a town hall meeting in Iowa on Tuesday that he believes a nuclear terrorist attack on the U.S. could be imminent and that the U.S. needs to hurry up and think of a way to stop it.

"If it is up to me, we are going to explain that an attack on this homeland of that nature would be followed by an attack on the holy sites in Mecca and Medina. Because that's the only thing I can think of that might deter somebody from doing what they otherwise might do," he said.

Despite his fringe status in the presidential race, Tancredo's statement prompted angry reactions among Muslims in countries deemed critical to the fight against Islamic extremism, notably Pakistan, where U.S. intelligence believes al-Qaida has regrouped.

In Pakistan, the country's Minister for Parliamentary Affairs Sher Afgan said Friday he would open debate next week on recent criticism of Pakistan from several quarters in the U.S., including remarks by Sens. Obama and Clinton and Tancredo.

It is a matter of "grave concern that U.S. presidential candidates are using unethical and immoral tactics against Islam and Pakistan to win their election," he said.

Obama, D-Ill., said last week he was willing to sit down with pariah leaders like North Korea's Kim Jong-il and Iran's Mahmoud Ahmedinejad and on Wednesday said he would send U.S. troops into Pakistan after Osama bin Laden and other extremists.

On Thursday, he ruled out the use of nuclear weapons in Afghanistan and Pakistan but was quickly derided by Clinton, D-N.Y., who signaled she would keep the option on the table.

At the State Department, diplomats fear that Tancredo's remarks, coupled with those of Obama and Clinton, will be seen as a broader trend of animosity by U.S. politicians to Muslims, especially in Pakistan, officials said.

In 1979, rumors that Israel was going to bomb Mecca and Medina led to the storming of the U.S. Embassy in Islamabad and the publication of cartoons of the Prophet Mohammed in European publications prompted violent protests two years ago.