WASHINGTON (Reuters) - Democrat Barack Obama put aside the victory celebrations on Wednesday and began crafting a White House team to help him lead a country mired in a deep economic crisis and two lingering wars.

The day after a sweeping election triumph that will make him the first black U.S. president, Obama named the leaders of his transition effort and offered U.S. Rep. Rahm Emanuel the job of White House chief of staff, party sources said.

Emanuel is expected to accept the offer, the source said, as Obama begins to lay the groundwork for a smooth takeover of power on January 20.

Obama led Democrats to a decisive victory on Tuesday that expanded their majorities in both houses of Congress, as Americans responded to his call for change and emphatically rejected Republican President George W. Bush’s eight years of leadership.

Raucous street celebrations erupted across the country, but Obama has little time to enjoy the triumph. Once in office, he will face immediate pressure to deliver on his campaign promises and resolve a long list of lingering problems.

“This victory alone is not the change we seek -- it is only the chance for us to make that change,” Obama told more than 200,000 jubilant supporters in Chicago’s Grant Park after his win.

Obama has vowed to withdraw U.S. troops from Iraq in the first 16 months of his term and to bolster U.S. troop levels in Afghanistan, but his first task will be tackling the U.S. financial crisis, the worst since the Great Depression.

World leaders will gather in Washington on November 15 for a summit on the global financial meltdown. The White House has said it does not expect the president-elect to attend, but Obama has not yet stated his plans.

Reports released on Wednesday showed the U.S. private sector jobs market deteriorated rapidly in October and the service sector contracted sharply, highlighting the economic challenges for Obama.

Appearing in the White House Rose Garden, Bush said he had spoken with Obama and congratulated him on an impressive victory that represented a “dream fulfilled” for civil rights. He pledged his cooperation in the transition.

Obama named three leaders of his transition effort -- his Senate chief of staff Pete Rouse, close friend and adviser Valerie Jarrett and Bill Clinton’s former White House chief of staff John Podesta.

The first-term Illinois senator has been planning for the transition for weeks and is expected to move quickly to fill positions at Treasury, the State Department and Homeland Security.

The job offer to Emanuel, a Democratic congressman from Chicago who worked in President Bill Clinton’s White House, came within hours of his victory, party sources said.

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A QUIET MORNING

But Obama’s first morning as president-elect was spent in more prosaic pursuits. He had breakfast at home in Chicago with his two daughters, then headed to the gym for a workout.

The son of a black father from Kenya and white mother from Kansas, Obama’s triumph over Republican rival John McCain on Tuesday was a milestone that could help the United States move beyond its long struggle with racism.

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Secretary of State Condoleezza Rice reflected the joy of many black Americans, calling Obama “inspirational” and praising the United States for its ability to surprise.

“As an African-American, I’m especially proud, because this is a country that’s been through a long journey, in terms of overcoming wounds and making race not the factor in our lives,” Rice told reporters.

“That work is not done, but yesterday was obviously an extraordinary step forward,” she said.

Many world leaders welcomed Obama’s victory. Some hailed it as an opportunity to restore a tarnished U.S. image; others urged him to help forge a new economic order. “Your election has raised enormous hope in France, in Europe and beyond,” French President Nicolas Sarkozy said.

Initial market reaction was muted. U.S. stocks fell by midday on Wednesday as worries about the weakening economy returned to center stage.

Obama won at least 349 Electoral College votes with two states still too close to call. He led McCain in the popular vote by 52 percent to 46 percent.

Democrats gained at least five Senate seats and about 20 in the House of Representatives, giving them a commanding majority in Congress and strengthening Obama’s hand. Four Senate seats remained undecided.

Americans celebrated in front of the White House to mark Obama’s win and Bush’s imminent departure. Cars jammed downtown Washington streets, with drivers honking their horns and leaning out their windows to cheer.

Thousands more joined street celebrations in New York’s Times Square and in cities and towns across the country.

“This is a great night. This is an unbelievable night,” U.S. Rep. John Lewis of Georgia, who was brutally beaten by police in Alabama during a civil rights march in the 1960s, said at an Atlanta celebration.