WASHINGTON  — President-elect Barack Obama plans to nominate Hillary Rodham Clinton as secretary of state after Thanksgiving, a new milestone for the former first lady and a convergence of two political forces who fought hard for the presidency.

One week after the former primary rivals met secretly to discuss the idea of Clinton becoming the nation’s top diplomat, an Obama adviser said Thursday that the two sides were moving quickly toward making it a reality, barring any unforeseen problems.

The senior adviser, speaking on condition of anonymity because the president-elect is not prepared to officially announce the nomination, said Obama believes Clinton would bring instant stature and credibility to U.S. diplomatic relations.

Obama is convinced the advantages of Clinton serving far outweighed potential downsides, the adviser said.

Transition aides said the two camps have worked out financial disclosure issues involving Clinton’s husband, former President Bill Clinton, and the complicated international funding of his foundation that operates in more than 40 countries. The aides said Obama and Hillary Clinton have had substantive conversations about the secretary of state job.

Clinton has been mulling the post for several days, but the comments from the transition aides suggested that Obama’s team does not feel she is inclined to turn it down. Clinton spokesman Philippe Reines would not comment, except to say that anything about Cabinet appointments is for Obama’s transition team to address.

Clinton would have to surrender her New York Senate seat, which she has held for eight years, to take the job.

The nomination would be a remarkable union between the former first lady who was an early favorite to win the presidency and the first-term senator who upset her in the primary and cruised to a general election victory. Such a high-profile seat in the Cabinet for Clinton also would be another achievement for the most accomplished former first lady in U.S. history, who has been the first presidential spouse to serve in the Senate and run for the White House herself.

Obama was picking other Cabinet posts as well. Obama has informally selected Washington lawyer Eric Holder as attorney general and former Senate Majority Leader Tom Daschle as health secretary and is likely to choose Arizona Gov. Janet Napolitano to be secretary of homeland security, Democrats said.

Any of the plans could be sidetracked by unexpected glitches in the final vetting process, officials note.