President Obama will close the office of political affairs at the White House, aides said, restructuring his organization to prepare for his re-election campaign, which is to start building a fund-raising and grass-roots operation based in Chicago by late March.

Mr. Obama has signed off on the plan to set up his campaign headquarters away from Washington, a first for a modern-day presidential re-election campaign. To avoid turf battles, chaotic communications and duplicated efforts, aides said, a significant realignment is underway in the West Wing, with the duties of the political office being taken up by the Democratic National Committee.

The president intends to formally declare his candidacy in about two months by filing papers with the Federal Election Commission, aides said. That step would allow him to start raising money and hiring a team of advisers, whose job it would be to make him the second Democrat since World War II to be elected twice to the White House.

While Mr. Obama is not expected to begin engaging in day-to-day campaign activity and attending fund-raisers until late spring or summer, advisers said, he has settled on the leadership for his re-election effort. The top three officials he has chosen all held important positions in his 2008 campaign, but have been elevated for 2012.

Jim Messina, a deputy White House chief of staff who has overseen operations in the West Wing and acted as a troubleshooter for the president, will manage the campaign [with]...two deputy campaign managers: Julianna Smoot, the White House social secretary who was the finance director of the 2008 campaign, and Jennifer O'Malley Dillon, executive director of the Democratic National Committee, who directed the battleground-state operation in 2008.