Obama vows to be 'relentless' in pursuit of those responsible for Libya attack

GOLDEN, Colo. -- President Obama at a campaign stop in Colorado on Thursday said his administration would be “relentless” in pursuing those who attacked the U.S. consulate in Libya.

Obama’s comments generally focused on how he and Republican nominee Mitt Romney differ on taxes and spending, but the president opened and closed his remarks for a second day in a row by talking about the outbreak of violence in the Middle East.

“We see on our televisions that there are still threats in the world and we have to stay vigilant,” Obama said. “That's why we have to stay relentless in pursuing those who attacked us this week.”

It remains unclear who was behind the attack in Libya that left four Americans dead, including U.S. Ambassador to Libya Christopher Stevens. Obama offered no clues while vowing to bring those responsible to justice.

Speaking to reporters earlier near the event site, White House Press Secretary Jay Carney said the administration would do everything it could to keep embassy personnel safe, as a new wave of protests occurred Thursday in Yemen.

"We are doing everything we can to protect the safety and security of personnel," Carney said. "(The) Yemeni government has sent additional security forces to our embassy. President Hadi has pledged additional resources and has made clear they won’t tolerate violence."

The press secretary said all employees at the diplomatic mission were safe and accounted for. But he noted that Friday is historically a day of protests and the White House is "watching closely" for more demonstrations and anticipates they may continue. He added that the White House had been in contact with governments in the region to make sure there was a clear understanding about the responsibility of host governments to protect diplomatic locations and personnel.

Carney added that that while he understood that the anti-Islam film trailer that sparked the protest was objectionable, "all leaders must draw a stark line against violence."

“We understand that it is hard for some people around the world to understand why the United States does not prevent movies like this from seeing the light of day. One, that’s impossible to do," Carney said.  “Furthermore, and more importantly, our country as a long tradition of free expression that is protected by law. Our government does not and cannot stop individual citizens from expressing their views."

Carney's remarks echoed those made earlier Thursday by Secretary of State Hillary ClintonHillary Diane Rodham ClintonSessions says FBI agent Peter Strzok no longer has his security clearance Melania Trump puzzles with 'I really don't care' jacket Grassley wants to subpoena Comey, Lynch after critical IG report MORE, who sought to tamp down anger over the film trailer. 

The president, meanwhile, focused most of his comments on the economy, which has been the central theme of the 2012 campaign.

Seeking to highlight a willingness to work across the aisle, Obama said he would “wash the car” and “walk the dog” with Republicans if that's what it would takes to strike a long-term budget and taxes deal for the nation.

He sought to portray Republicans as obstructionists, and called Romney’s position on taxes “the same old sales pitches.”

“Tax cuts in good times, tax cuts in bad times, tax cuts in times of peace, tax cuts in time of war,” Obama said, speaking to a crowd against a Rocky Mountain backdrop and repeating a line he's used in recent days.

But he changed it up a bit to reflect the launch of the new iPhone: “You want a restaurant reservation? You don't need the new iPhone, there's a tax cut for that.”

As he has done since speaking at the Democratic National Convention last week, Obama told the crowd he “won't pretend that the path I'm on is easy.”

Bill ClintonWilliam (Bill) Jefferson ClintonThe case for a ‘Presidents’ Club’ to advise Trump After FBI cleared by IG report, GOP must reform itself Bill Clinton hits Trump administration policy separating immigrant families in Father's Day tweet MORE reminded us last week it's going to take a few more years to deal with the challenges that have built up,” he said. “To be fair, the other side has a plan. But as President Clinton pointed out, it doesn't have arithmetic in it.

“Your calculators are going to go out on you if you try to add all that stuff, and I refuse to ask middle class families to pay more so I can pay less,” he added. “I will not turn Medicare into a voucher just to give tax cuts to the wealthy. No American should ever have to figure their golden years at the mercy of the insurance companies. You should retire with dignity and respect.”

Obama's campaign events in Nevada and Colorado have been overshadowed by the violence overseas, which also have included incidents at the U.S. embassies in Egypt and Yemen.

While the Libya attack has aroused suspicion, administration officials say other attacks were outgrowths from protests over a U.S.-financed, anti-Islam film trailer released on YouTube.

During a briefing with reporters on Thursday, White House press secretary Jay Carney said the American government "had nothing to do with this movie.”

“We reject its messages and its contents,” he said. “We find it disgusting and reprehensible. America has a history of religious tolerance and respect for religious beliefs that goes back to our nation's founding. We are stronger because we are home to people of all religions, including millions of Muslims.”

This post was updated at 3:06 p.m.