WARSAW, Poland - Holding out Poland's transformation to democracy as a model for the world, President Barack Obama on Saturday exhorted Western allies and the American public alike to extend their support, energy and vision to those now reaching for democracy in the Middle East and North Africa.

Obama wound up his six-day trip to Europe with a message aimed squarely at the people of the United States, saying that in a time of tight budgets, "I want the American people to understand we've got to leave room for us to continue our tradition of providing leadership when it comes to freedom, democracy, human rights."

Obama, in a brief news conference with Polish Prime Minister Donald Tusk, assured Americans that he spends the bulk of each day worrying about the U.S. economy and how to strengthen it and create jobs. But he coupled that with the message that it is a U.S. obligation to support democracy around the globe, one that pays dividends in the form of a safer and more prosperous world.

Speaking with urgency in his voice, Obama said that while no outside country can "impose change" on another, "We can really help. We can facilitate. We can make a difference."

His message was a tacit answer to simmering sentiment that America should cut back on foreign assistance at a time when it is grappling with deficit troubles at home. In fact, foreign aid makes up less than 1 percent of the federal budget.

Earlier in the day, Obama met with Poland's president, Bronislaw Komorowski, and with a team of Poles, including veterans of the Solidarity movement, who recently visited Tunisia to share their advice on how to build a democracy. A popular uprising in Tunisia led to the overthrow of a longtime autocrat and sparked the protest movements that still sweep through the region.

Poland, Obama said, "has gone through what many countries want to now go through, and has done so successfully."

The president also offered reassurances to the Poles that his efforts to "reset" relations with Russia would not come at the expense of the security of Poland or other nations in Central and Eastern Europe.

He said improved U.S. contacts with Russia "has benefited the region ... because it's reduced tensions and has facilitated genuine dialogue about how each country can move forward."

Citing struggles for democracy in Poland's own neighborhood, Obama had tough words for Belarus President Alexander Lukashenko. He praised Poland's assistance to Belarusian people and its efforts to encourage changes in Belarus.

"President Lukashenko has shown a total disregard for democratic values, the rule of law, and the human rights of his own people," Obama said.

Timed to coincide with Obama's visit, the United States and Poland completed an agreement that will place a U.S. Air Force detachment in Poland beginning in 2013. The presence of U.S. warplanes on Polish soil is designed to improve the ability of U.S. and Polish armed forces to cooperate as members of the NATO alliance.

"The order of magnitude is not really large, but the gesture is very significant," Tusk said.

Obama did not, however, bring with him a solution to a longstanding irritant to the Poles: their exclusion from a visa waiver program for those traveling to the United States. Many Poles feel that their strong support for the U.S. and their contributions to the wars in Iraq and Afghanistan should have won them the privilege of visa-free travel to the United States.

Obama said Poland doesn't qualify for the waiver based on current law but promised that he was working to change that.

Obama's four-nation tour of Europe was aimed at strengthening the U.S. alliance with its Western allies, and encouraging them to shoulder greater responsibility in world affairs. He made stops in Ireland, England, France and Poland, at the final stop joining a summit of Central and Eastern European leaders.

In Ireland, Obama explored his Irish ancestry on his mother's side and spoke to throngs in Dublin about Ireland's contributions to the world.

In England, he and his wife, Michelle, were honored with all the pomp and ceremony of a state visit by Queen Elizabeth II, and he consulted with Prime Minister David Cameron about a range of foreign policy matters, including the war in Afghanistan and the so-called Arab spring movement.

Both men then headed to France for a two-day summit for leaders of the Group of Eight industrialized nations, which devoted considerable focus to how rich nations can help stabilize and foster democracy in Arab countries.

The president, who began his trip by exploring his Irish ancestry, at the end managed to find a Polish link as well, by virtue of his connections to Chicago's large Polish population.

"If you come from Chicago and you haven't become a little bit Polish, something's wrong with you," he joked.

Tusk, for his part, told Obama, "We feel in Poland that you are one of us."

Tom Mann, a scholar at the Brookings Institution in Washington, said Obama's trip may have incrementally boosted his image with Americans as a leader on foreign policy but was "more of a boost for him among European leaders, which may help in pursuing U.S. interests in the Middle East and elsewhere."

Obama had first planned to come to Poland last year for the funeral of President Lech Kaczynski, who was killed in a plane crash along with other Polish leaders. But Obama's visit was scrapped six hours before his departure because of a volcanic ash cloud over Europe that disrupted air travel. The president visited a memorial to the 96 who died in the crash on his way out of town on Saturday.

After a long week with a crowded agenda, Obama seemed more than ready to head home. The tired-looking president paused midway through his answer to a Polish reporter to ask the man to repeat parts of his question.

The president had been counting down the days until his return to Washington.

"One more day," he told reporters traveling with him Friday in France.

Associated Press writers Julie Pace, Vanessa Gera and Monika Scislowska contributed to this report.