Chris Bowers, who writes on the OpenLeft.com blog, complained that the foreign policy lineup was a center-right team. “I feel incredibly frustrated,” Mr. Bowers wrote last week. “Progressives are being entirely left out of Obama’s major appointments so far.”

Image Senators Lamar Alexander, left, and Mitch McConnell, at lectern, say the Obama transition team is off to a cooperative start. Credit... Gerald Herbert/Associated Press

It is hardly unusual for an incoming president to extend his hand to members of the opposing party. (Mr. Obama is spending a good bit of time, aides said, studying the approach of President Abraham Lincoln.) What is far more difficult, though, is sustaining the radiance of the bipartisan honeymoon, a difficulty President Bush encountered eight years ago after early signs of goodwill to Senator Edward M. Kennedy, Democrat of Massachusetts, in their pursuit of an education overhaul.

Mr. Obama’s challenge is no different  it is perhaps even more acute  as he works to straddle the partisan divide that has grown deeper over the last eight years. Advisers said he was well aware of the balancing act awaiting him, particularly as he worked to avoid disappointing or angering Democrats on the left, a constituency that was vital to his winning the party’s nomination.

“Even though the majorities are big, the challenges are of such a magnitude that we’re all inheriting, it’s going to require bipartisanship to solve,” Mr. Emanuel said in an interview after completing a round of meetings with Congressional Republicans. “We’re not lip-synching bipartisanship here.”

Mr. Emanuel, who was formerly the No. 4 Democrat in the House and helped expand the party’s majority in Congress, signaled to Republicans that the president-elect wanted to work alongside them. He handed out his personal cellphone number, urging them to call at any hour if they needed to reach him, and he asked them to submit their ideas for the economic recovery plan and other issues of potential agreement.

Even when they were in the majority, Republicans were often frustrated with the Bush administration’s lack of outreach to Congress. They said Mr. Emanuel’s arrival on Capitol Hill less than three weeks after the election  though no breakthroughs were made on issues  sent a good preliminary message.