WASHINGTON (AP) — Dramatically hardening the U.S. reaction to Iran's disputed elections and bloody aftermath, President Barack Obama condemned the violence against protesters Tuesday and lent his strongest support yet to their accusations the hardline victory was a fraud.

Obama, who has been accused by some Republicans of being too timid in his response to events in Iran, declared himself "appalled and outraged" by the deaths and intimidation in Tehran's streets — and scoffed at suggestions he was toughening his rhetoric in response to the criticism.

He suggested Iran's leaders will face consequences if they continue "the threats, the beatings and imprisonments" against protesters. But he repeatedly declined to say what actions the U.S. might take, retaining — for now — the option of pursuing diplomatic engagement with Iran's leaders over its suspected nuclear weapons program.

"We don't know yet how this thing is going to play out," the president said. "It is not too late for the Iranian government to recognize that there is a peaceful path that will lead to stability and legitimacy and prosperity for the Iranian people. We hope they take it."

Obama borrowed language from struggles throughout history against oppressive governments to condemn the efforts by Iran's rulers to crush dissent in the wake of June 12 presidential elections. Citing the searing video circulated worldwide of the apparent shooting death of Neda Agha Soltan, a 26-year-old young woman who bled to death in a Tehran street and now is a powerful symbol for the demonstrators, Obama said flatly that human rights violations were taking place.

"No iron fist is strong enough to shut off the world from bearing witness to peaceful protests of justice," he said during a nearly hourlong White House news conference dominated by the unrest in Iran. "Those who stand up for justice are always on the right side of history."

The eighth extended news conference of Obama's presidency also veered into the intricacies of the health care reform debate, the effectiveness of the economic stimulus package and a revealing personal moment in which he acknowledged he still is an occasional smoker despite trying to quit.

"I would say I'm 95 percent cured, but there are times where I mess up," the president said the day after signing an anti-smoking bill into law. He said he doesn't smoke daily, nor does he light up in front of his children.

The past 10 days in Iran have posed the strongest challenge to that nation's clerical rule since the system was established 30 years ago in the 1979 Islamic revolution. Before Tuesday, Obama mostly kept to a modulated response, calculating that, given Iranians' distrust of American involvement in their country, anything viewed as internal meddling from the White House would do the demonstrators more harm than good.

He also is deeply interested in preserving his promised policy concerning Iran and the threat its nuclear program poses: He contends the danger has only grown through decades of ruptured diplomatic relations between the U.S. and Tehran, particularly in the past eight years under President George W. Bush, and it is time to try to change that by re-establishing direct talks.

But Obama has been taken to task by some Republicans, accused of being too passive. Even with Iran's blackout of foreign press and attempted communications shutdowns, chaotic images of riot police beating and shooting protesters have seized the world's attention. At least 17 people have been killed.

Last Sunday, Sen. Lindsey Graham, R-S.C., said: "The president of the United States is supposed to lead the free world, not follow it. He's been timid and passive more than I would like."

Obama chose a less cautious approach on Tuesday, more directly challenging Iran's leaders to ease off and holding out the possibility of consequences if they do not.

"The Iranian government should understand that how they handle the dissent within their own country, generated indigenously, internally, from the Iranian people, will help shape the tone, not only for Iran's future, but also its relationship to other countries," Obama said.

He made clear that one recent overture to Iran — the authorization for U.S. embassies to invite Iranian officials to Independence Day parties — was likely to disappear without changes. "That's a choice the Iranians are going to have to make," Obama said.

With an array of U.S. sanctions already in place against Iran, there are few options at Obama's disposal other than withdrawing his offer to talk. Regardless, Obama said it's too early for him to be more specific. "We are going to monitor and see how this plays itself out before we make any judgments about how we proceed," he said.

Answering a question from a Huffington Post writer that was solicited by the White House in advance, Obama was plainer than ever that the protesters' beliefs that the election was stolen from opposition candidate Mir Hossein Mousavi may be legitimate. The government declared an overwhelming re-election victory for President Mahmoud Ahmadinejad and, while promising to look into scattered reports of irregularities, has ruled out annulling those results.

"We can't say definitively what exactly happened at polling places throughout the country," Obama said. "What we know is that a sizable percentage of the Iranian people themselves, spanning Iranian society, consider this election illegitimate. It's not an isolated instance, a little grumbling here or there. There is significant question about the legitimacy of the election."

In Obama's comments, there also was a notable shift away from previous respectful references to Iran's most powerful cleric, Ayatollah Ali Khamenei, as the "Supreme Leader." Obama didn't use the term on Tuesday.

Asked if his stronger language was influenced by pressure from Republicans such as Graham and Sen. John McCain, Obama scoffed: "What do you think?" And he shot back at GOP critics: "Only I'm the president of the United States."

Advisers realize the new tone poses a risk that the U.S. president will become a scapegoat for Iran's leaders — just what Obama has sought to avoid. Administration officials, speaking on condition of anonymity to describe a sensitive strategy, said the disturbing images of the past few days warranted the tougher stance.

"I congratulate him for that, and we need to keep the pressure on them," House Minority Leader John Boehner, R-Ohio, said after the news conference.

The president took the podium after a troublesome week for his five-month-old administration.

Fellow Democrats are fretting about the jaw-dropping cost estimates of reforming health care, a series of polls have underscored deep unease among independents and moderates over the soaring deficit, and his overall approval rating — while still high — has been slipping.

Obama pushed lawmakers to deliver on his ambitious goals of overhauling health care and energy, both in peril.

Also, acknowledging that the unemployment rate is going to climb over 10 percent, Obama said he's not satisfied with progress so far from the $787 billion economic stimulus plan passed in January. He said aid must get out faster and some programs — like one aimed at helping save some homeowners from foreclosure — need adjustment.

Still, asked if he would call for more stimulus spending, he said: "Not yet, because I think it's important to see how the economy evolves and how effective the first stimulus is."

On health care, Obama left open the door to abandoning his demand that people under any revamped system have the option of choosing coverage from a government-funded program.

"We are still early in this process," he said. "So, you know, we have not drawn lines in the sand other than reform has to control costs and that it has to provide relief to people who don't have health insurance or are underinsured."

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AP National Security Writer Anne Gearan and AP writers Philip Elliott and Ben Feller contributed to this story.