WASHINGTON -- Foreign affairs intruded dramatically on the presidential race Wednesday as Republican presidential candidate Mitt Romney issued a blistering political assault on President Barack Obama and said his administration had severely miscalculated in the early hours after assaults on U.S. diplomatic outposts in North Africa.

Obama didn't respond to Romney when he spoke moments later from the White House. The president condemned the attack moments later in a televised statement from the White House and eulogized Chris Stevens, the 52-year-old U.S. ambassador to Libya, who was slain in the eastern Libyan city of Benghazi. Three other American diplomatic personnel also perished.

Obama, flanked by Secretary of State Hillary Clinton, said: "Make no mistake. Justice will be done." He made no mention of Romney's political assault.

The Republican challenger, who has surrounded himself with foreign policy experts from the George W. Bush administration, said Obama's foreign policy leadership had failed because he had allowed the U.S. government to send "mixed signals" about the attacks on the American embassy in Cairo and its consulate in Benghazi in eastern Libya.

"They clearly sent mixed messages to the world. The statement that came from the administration -- and the embassy is the administration -- the statement that came from the administration was a statement which is akin to apology. And I think was a severe miscalculation," Romney said.

Until the attacks by angry mobs on U.S. diplomatic missions, the tightly contested race had focused on the struggling U.S. economy and high unemployment.

The U.S. Embassy in Cairo had issued a statement hours before the Americans' death in Libya was reported calling for calm both there and in Cairo, saying, in part, that it condemns "the continuing efforts by misguided individuals to hurt the religious feelings of Muslims - as we condemn efforts to offend believers of all religions."

That prompted a Romney statement voicing outrage over the attacks and what was then thought to have been the death of the American consulate worker. He has charged throughout his campaign for the White House that Obama has been soft on American opponents around the globe.

"It's disgraceful that the Obama administration's first response was not to condemn attacks on our diplomatic missions, but to sympathize with those who waged the attacks," Romney's statement said.

In response to Romney, Obama campaign spokesman Ben LaBolt said in an email early Wednesday, "We are shocked that, at a time when the United States of America is confronting the tragic death of one of our diplomatic officers in Libya, Gov. Romney would choose to launch a political attack."

By Wednesday morning, once the tragic events were fully understood, Obama issued a statement in which he said: "I strongly condemn the outrageous attack on our diplomatic facility in Benghazi, which took the lives of four Americans, including Ambassador Chris Stevens. Right now, the American people have the families of those we lost in our thoughts and prayers."

Obama also said: "While the United States rejects efforts to denigrate the religious beliefs of others, we must all unequivocally oppose the kind of senseless violence that took the lives of these public servants."

Clinton spoke Wednesday morning, expressing 'profound sadness' over deaths of the 4 U.S, personnel in Libya.

The violence against American diplomatic missions in the two North African countries compounded a controversy that arose earlier Tuesday over a dispute about whether Obama and Israeli Prime Minister Benjamin Netanyahu would meet next week in New York.

That prompted Obama to spend an hour Tuesday night talking by phone with the Israeli leader who had publically chastised the world, the U.S. included, for failing to draw "red lines" against Iran's nuclear program. The United States, Israel and many allies accuse Tehran of trying to build a nuclear weapon under the cover of what Iran insists is a program to build nuclear facilities for electricity generation and medical research.

Netanyahu has threatened to attack Iran and wants to the United States to join in. Obama believes there is still time to reach a diplomatic solution, although he has said the U.S. will not allow Tehran to have a nuclear weapon and that no American response will be taken off the table.

Foreign policy had been only a seldom-mentioned subtext in the brutal campaign for the White House. While polls show Obama is favoured as the candidate best equipped to handle U.S. diplomacy and security affairs, voters are most concerned about the struggling U.S. economy and high unemployment.

With domestic issues suddenly overshadowed, if only temporarily, the candidates planned to resume their deeply partisan campaigns Wednesday. Negative ads were ready again to consume the television air waves and the candidates were spreading out across the battleground states that will decide the Nov. 6 election. Polls show that Obama has opened up a slight lead over Romney in the aftermath of the Republican and Democratic national conventions. The three presidential debates, starting on Oct. 3, give Romney his best chance to pull ahead.