President Obama's appearance before the media Tuesday highlighted how much his second and final term remains consumed by the unfinished business of his first.

From his policy toward Syria to health care legislation to his inability to close the prison at Guantanamo Bay, Cuba, Obama faced many of the same questions from journalists that have defined his time in office.

He used long, sometimes defensive answers to portray himself as undaunted by the unresolved challenges, yet also limited in his ability to secure the changes he has sought for years because of his continuing confrontation with a divided Congress.

That self-assessment of his political power also is largely consistent with his message to the nation since Democrats lost control of the House in 2010. His domestic agenda has largely ground to a halt since then.

Now his window for progress in Congress is even smaller than it once was, and may likely close entirely by the 2014 midterm elections unless his party can retake control of both chambers. It was unclear Tuesday how he intends to revive his political prospects after setbacks on gun control and fiscal negotiations to avoid across-the-board spending cuts that he acknowledged are undermining the economy.

"Rumors of my demise may be a little exaggerated at this point," Obama said during the news conference, in a phrase reminiscent of Bill Clinton's 1995 assertion of his own relevance after his party lost the House the previous year.

But in responding to a reporter's assertion that he appears powerless in dealing with Congress, Obama responded, "You seem to suggest that somehow, these folks over there have no responsibilities and that my job is to somehow get them to behave."

"That's their job," he said.

The news conference - Obama's third domestic one this calendar year - fell on the 100th day of what already has been a difficult final term.

Just this month, Obama lost his bid for stricter gun control, an issue on which he used emotion and outside-the-Beltway appeals for action following the December shooting in Newtown, Conn., which killed 20 children and six adults.

Days after that Senate defeat, the first large-scale bombings in the post-Sept. 11, 2001 era killed three and wounded more than 200 others near the finish line of the Boston Marathon - an attack allegedly carried out by a pair of young Muslims "self-radicalized' through anger over the American wars abroad.

Obama acknowledged Tuesday that preventing such attacks may be harder than defending against those directed by foreign terrorist organizations, especially in a way that protects American civil liberties .

Obama also faces a new challenge abroad, given the mounting evidence that Syria's government used chemical agents against the population.

Last week, his administration informed Congress that it has "varying degrees of confidence " in evidence suggesting that chemical weapons have been used in Syria's civil war, which has killed more than 70,000.

Obama had warned previously that President Bashar al-Assad would cross a "red line" if he used such weapons. Now Obama is faced with how to respond at a time when, in his words "the tide of war is receding" after his departure from Iraq and withdrawal deadline in Afghanistan. So far he appears to be hoping to buy some time.

"What we now have is evidence that chemical weapons have been used inside of Syria, but we don't know how they were used, when they were used, who used them," Obama said.

Then, tacitly invoking the legacy of the Iraq war when U.S. credibility suffered because the Bush administration's promised weapons of mass destruction never turned up, Obama told a war-weary nation, "If we end up rushing to judgment without hard, effective evidence, then we can find ourselves in the position where we can't mobilize the international community to support what we do."

Although public support for direct intervention in Syria is low, Obama faces the challenge of ensuring American credibility in how he proceeds. Iran, in particular, is watching carefully for what Obama means by red lines, given his statement that he will not allow the Islamic Republic to developing nuclear weapons.

But Obama offered few clues on Tuesday to how he intends to proceed with any of the unfinished items on his agenda.

He pledged to reengage Congress in his effort to close the military prison at Guantanamo Bay, Cuba, where a prisoner hunger strike has highlighted again the legal ambiguities surrounding their detention. Obama has been working to close Guantanamo since the day after he took office and again he cited Congress as the chief obstacle.

"Congress determined that they would not let us close it and despite the fact that there are a number of the folks who are currently in Guantanamo who the courts have said could be returned to their country of origin or potentially a third country," Obama said. "I'm going to go back at this."

Even his health care law - the signature legislation of his presidency - is a work in progress. Obama defended what is a complicated implementation process now underway that will extend health care to the estimated 15 percent of the population that does not have it.

In assuring the public that the process is not nearly as messy as some members of Congress have portrayed, Obama said anyone who has health insurance will likely see no further changes as the law takes full effect. He also warned of challenges ahead.

"Even if we do everything perfectly, there will still be glitches and bumps," Obama said. "But if we stay with it and we understand what our long-term objective is, which is making sure that in a country as wealthy as ours, nobody should go bankrupt if they get sick."

As Obama continues to try to turn his re-election into political power inside Washington, it appears "staying with it" is the core of his strategy in a still-divided capital, in counter-terrorism policy, and in his diplomacy in the tumultuous Middle East.