(CNN) -- President-elect Barack Obama's top adviser insisted Sunday that Obama's economic plan would be big enough to handle the country's financial challenges, but he declined to speculate about how large the plan would need to be.
Senior adviser David Axelrod says it will take the "best people we can find" to carry out Obama's economic plan.
During the presidential campaign, Obama proposed a $175 billion stimulus package over a two-year period, but some of his economic advisers have said recently that the package would need to be much larger.
Asked if Obama would scale up the package, given the economic conditions, Obama's incoming senior adviser, David Axelrod, said he thinks Obama is "going to do what's necessary."
"I'm not going to throw a figure out here. What he said is, he wants a plan big enough to deal with the large challenges we face. And I think there's a growing consensus across the spectrum among economists that we're going to have to do something big," Axelrod said Sunday on ABC's "This Week."
Obama on Saturday offered an outline of his economic recovery plan to create 2.5 million jobs by 2011, saying American workers will rebuild the nation's roads and bridges, modernize its schools and create more sources of alternative energy.
Details of the plan are still being worked out by his economic team, Obama said, but he hopes to sign the two-year, nationwide plan shortly after taking office January 20.
Obama noted he will need support from both Democrats and Republicans to pass such a plan, and said he welcomes suggestions from both sides of the aisle.
"But what is not negotiable is the need for immediate action," he said Saturday.
Axelrod said it will take "the best people we can find, the best minds in our country" to carry out Obama's economic plan.
In an interview on "Fox News Sunday," he said New York Federal Reserve President Tim Geithner and former Treasury Secretary Larry Summers are among the those people.
Summers, who lost out to Geithner for the Treasury post, is expected to be the top economic adviser in the Obama White House, two sources close to the transition said Saturday.
Summers, who was Treasury secretary in the Clinton administration, will be named chief of the National Economic Council by Obama at an event in Chicago, Illinois, on Monday, the sources said.
Geithner's nomination to be Treasury secretary, the top economic post in the Cabinet, will also be officially announced at Monday's event, the sources said. Axelrod, on ABC, referred to Geithner's "pending appointment." Watch panelists weigh in on possible Cabinet choices »
In another Cabinet decision, two Democrats close to the transition told CNN that New Mexico Gov. Bill Richardson is expected to be nominated as secretary of commerce, pending the final vetting process.
Richardson, one of the leading Hispanics in the Democratic Party, had been seeking the secretary of state post but lost out to Sen. Hillary Clinton. Obama aides have told CNN that Obama is "on track" to nominate Clinton as his secretary of state after Thanksgiving.
The precise timing of the announcement of Richardson's appointment is unclear.
Two Richardson advisers said privately that Richardson had been hoping the State Department leadership post would be his prize after facing political heat for picking Obama over Clinton, but the governor is willing to accept another post in hopes that he will move up in the Cabinet later in the administration.
Richardson was energy secretary and U.S. ambassador to the United Nations in Bill Clinton's administration.
Obama's pick will now mean that at least three former rivals from the Democratic presidential primaries will be in senior posts in the Obama administration: Richardson, Clinton and Vice President-elect Joe Biden.
The Obama transition team on Saturday also announced several key appointments to his communications team.
Ellen Moran, the executive director of EMILY's List, will be Obama's communications director. Moran worked for the AFL-CIO, coordinating "Wal-Mart corporate accountability activities," before returning to EMILY's, an organization dedicated to helping Democratic women get elected to office.
Robert Gibbs, an Obama campaign spokesman who also has been spokesman for the transition, will become Obama's press secretary -- one of the most highly visible roles in the administration.
Gibbs -- an Auburn, Alabama, native who has worked for Sen. Fritz Hollings, the Democratic Senatorial Committee and Sen. John Kerry's presidential campaign -- was communications director, then a senior strategist, for the Obama campaign.
Dan Pfeiffer, current communications director with the transition team, will be Obama's deputy communications director. He began work with the Obama campaign in January 2007 as traveling press secretary before returning to Chicago to work as communications director.
"These individuals will fill essential roles, and bring a breadth and depth of experience that can help our administration advance prosperity and security for the American people," Obama said in a written statement. "This dedicated and impressive group of public servants includes longtime advisors and a talented new addition to our team, and together we will work to serve our country and meet the challenges of this defining moment in history."
CNN White House correspondent Ed Henry contributed to this report.