WASHINGTON - President Barack Obama toughened his criticism of Iran on Tuesday for its crackdown on anti-government protesters, harshly condemning the violence and declaring scenes of death in Tehran heartbreaking.

At his fourth White House news conference, Obama also said he was still optimistic about the prospects in Congress for an overhaul of the costly U.S. healthcare system and urged lawmakers to pass a comprehensive climate change bill.

The Democratic president, facing heavy criticism from Republicans that he was being too timid in backing street protests over Iran's contested election, said the United States was appalled and outraged by the violence.

I strongly condemn these unjust actions, and I join with the American people in mourning each and every innocent life that is lost, Obama said.

He called the video of an Iranian women killed in the streets, which has become a staple of news coverage of the protests, heartbreaking and said it made clear the violence against the protesters was fundamentally unjust.

In 2009, no iron fist is strong enough to shut off the world from bearing witness to the peaceful pursuit of justice, he said.

Asked why it took him so long to express his outrage, Obama said the U.S. approach had been consistent and he did not want to hurt the protesters by aligning them with the United States.

Ultimately, the most important thing for the Iranian government to consider is legitimacy in the eyes of its own people, he said.

But Obama declined to spell out any potential consequences for Tehran of the crackdown, and said there was still a path available to Iran in which it could operate within the international community.

SETBACKS AND POLL DECLINES

Obama has faced setbacks on central legislative goals and a bout of bad news in public opinion polls in the last week, and he became testy at times when pressed by reporters. He rejected suggestions he was responding to attacks by Republicans such as former presidential rival Senator John McCain.

Obama said he still believed Congress would pass an overhaul of the healthcare system, and a government-run health insurance plan made sense as part of the package, he said.

Obama is battling growing concerns over the price tag -- at least $1 trillion and possibly far more -- on his reform plan and proposals for a government-run insurance plan that would compete with private insurers.

This is legislation that will be paid for. It will not add to our deficits over the next decade. We will find the money through savings and efficiencies within the health care system, he said.

A wave of new public opinion polls show declining satisfaction with Obama's policies and concerns about growing federal debt, although the president remains personally popular.

A newly released Washington Post/ABC News poll showed only about half of Americans believe the president's $787 billion stimulus package will boost the economy and nine of every 10 Americans are at least somewhat concerned about the size of the deficit.

Obama said he was not surprised by the polls and the American people have a right to expect results on the economy, which he said will take time to turn around. He said there was no need for a second stimulus package yet.

In the absence of the stimulus, I think our recession would be much worse, he said.

The climate change bill, which faces a vote in the House of Representatives on Friday, was needed to make the United States the leader in a clean engine economy, he said.

This energy bill will create a set of incentives that will spur the development of new sources of energy, including wind, solar, and geothermal power, Obama said. This legislation is extraordinarily important for our country.

The climate bill's chances of passage are cloudy in the Senate, although more positive in the House.

Obama also praised the work of Federal Reserve Chairman Ben Bernanke, whose term expires in January.

Obama was scheduled to meet with later on Tuesday with Chilean President Michelle Bachelet.

(Additional reporting by David Alexander, Ross Colvin, Doug Palmer, Tabassum Zakaria, Andy Sullivan and Andrew Quinn; Editing by Patricia Zengerle)

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