Sen. Edward Kennedy will return to Washington for his first extended stay since being diagnosed with brain cancer in May, an aide said Tuesday.

Kennedy spokeswoman Melissa Wagoner said the 76-year-old senator planned to leave the family's Hyannis Port compound on Tuesday afternoon for the District of Columbia, weather permitting. Wagoner said he would return to Cape Cod around Thanksgiving.

Kennedy will continue to receive cancer treatment while at his home in Washington. Wagoner said doctors were pleased with the senator's progress.

Kennedy had a seizure in May and underwent surgery in June for a malignant brain tumor. After undergoing six weeks of chemotherapy and radiation treatment, he has been steadily increasing his public activity.

Kennedy surprised his colleagues in July when he returned to Capitol Hill to vote on a Medicare bill. He also made a dramatic speech supporting Democratic presidential candidate Barack Obama at the party's convention in Denver.

In early September, Kennedy announced he would not return to the Senate until January, but has since held video conferences with his staff and members of the Senate Committee on Health, Education, Labor and Pensions, which he leads.

The senator has been working to lay the groundwork for a breakthrough next year on health care reform, a cause he has championed for decades. Aides have said he has held several video conferences with lawmakers and staff on the issue, and his staff has held more than a dozen meetings in recent weeks with various advocacy and interest groups that will help influence the debate.

Wagoner said it is possible Kennedy could be back working in his Senate office if Congress returns for a post-election lame duck session to craft an economic stimulus bill.

"It's possible, but any decisions on something like that won't be made until the time gets closer," Wagoner said. "Senator Kennedy will be continuing to work on health care with other members, Obama folks and others."

Late last month, Kennedy was taken by ambulance to a hospital near his Cape Cod home after complaining of feeling ill. A statement issued by his office attributed the episode to a change in medications. He returned to his home about three hours later.