President Barack Obama used his biggest speech of the year to try to revive his stagnant second term, announcing executive orders aimed at boosting economic security for Americans while bypassing the partisan gridlock that has bedeviled his presidency.

He told Congress he will act on his own "whenever and wherever" he can.

Also, in a State of the Union speech otherwise dominated by domestic issues, Obama warned Congress he would veto any sanctions bill that threatens to derail talks with Iran, even as he acknowledged that the talks may not succeed.

Facing strong Republican opposition and low approval ratings after the worst year of his presidency, Obama wasn't unveiling major initiatives in his speech. Instead, he announced modest actions that don't need congressional approval, such as raising the minimum wage for new federal contracts, helping the long-term unemployed find work and expanding job training programs.


Those executive orders highlight themes Democrats are expected to press in the November congressional election as they cast themselves as champions for lower- and middle-class Americans who have been left behind in the economic recovery, even as US corporations and financial markets have surged.

"Inequality has deepened. Upward mobility has stalled," Obama said. "The cold, hard fact is that even in the midst of recovery, too many Americans are working more than ever just to get by - let alone get ahead. And too many still aren't working at all. "

Obama's approval ratings are down sharply over the past year. An AP-GfK poll this month found 45 per cent of those surveyed approved Obama and 53 per cent disapproved. That's worse than a year ago, when 54 per cent approved and 42 per cent disapproved, but an improvement over his ratings in December, when 58 per cent disapproved of his job performance.

His ratings tumbled with the botched rollout of his signature health care overhaul. Republicans are focusing on that issue as they try to win control of the Senate and protect their majority in the House of Representatives.

In the official response to Obama, a top House Republican says the president's policies are making life hard for Americans. In advance excerpts of her speech, Cathy McMorris Rodgers says the Republican vision "champions free markets - and trusts people to make their own decisions, not a government that decides for you."

Still, Republicans politely, if not enthusiastically, applauded the president as he spoke before the full Congress and an audience of Cabinet members, ambassadors and millions of viewers in prime television time.

The negotiations to stop Iran's nuclear program dominated the foreign policy part of the speech. Obama said the talks will be difficult and if they fail, he will call for more sanctions. "But if Iran's leaders do seize the chance, then Iran could take an important step to rejoin the community of nations, and we will have resolved one of the leading security challenges of our time without the risks of war."

On Syria, he also pledged "to work with the international community to usher in the future the Syrian people deserve - a future free of dictatorship, terror and fear."

Obama said the United States "will continue to focus on the Asia-Pacific" and called the alliance with Europe "the strongest the world has ever known." Regarding the turmoil in Ukraine, he said "we stand for the principle that all people have the right to express themselves freely and peacefully, and have a say in their country's future."

But most of his address was devoted to domestic issues, which weigh most heavily on the minds of Americans.

Republicans have thwarted most of Obama's initiatives, including on gun control and climate change, and this year's elections make it even less likely that they will rally behind his proposals. Still, the partisan fighting has eased somewhat from when Republicans shut down the government for 16 days last fall and brought the country to the brink of default.

Obama has some hope of winning support for a theme he discussed in the speech, overhauling America's immigration system, as Republicans try to build support among the country's growing Hispanic population.

But the White House sees a robust rollout of executive actions as the most effective way to show the public that Obama still wields power in the sixth year of his presidency.

Obama said he is eager to work with Congress on measures requiring lawmakers' approval. "But America does not stand still - and neither will I. So wherever and whenever I can take steps without legislation to expand opportunity for more American families, that's what I'm going to do," he said.

Yet much of what the president can do on his own is limited, as evidenced by the minimum wage initiative. The executive order will increase the minimum hourly payment for new federal contract workers from $7.25 to $10.10. But the measure affects only future contracts, and its immediate impact will be minimal.

"The question is how many people, Mr. President, will this executive action actually help?" said the top House Republican, John Boehner. "I suspect the answer is somewhere close to zero."

Obama will renew his call for Congress to pass a minimum wage increase for all Americans, a proposal that gained little traction after he first announced it in last year's address. Some Republican lawmakers have indicated an interest in working on income inequality and economic mobility issues.

Some Republicans have warned that the president's focus on executive orders could backfire by angering party leaders who already don't trust the White House.

"The more he tries to do it alone and do confrontation, the less he's going to be able to get cooperation," said John Feehery, a former top House Republican aide.

- AP