Barack Obama (web|news|bio) has agreed to deliver the commencement address at Wesleyan University in place of Sen. Edward Kennedy, who pulled out Thursday after finding out he had brain cancer. Kennedy, 76, had planned to address the graduates - including stepdaughter Caroline Raclin - Sunday in Middletown, Conn. The commencement exercises coincide with 25th reunion festivities for his son, Edward Kennedy Jr., who graduated from the school in 1983. The Massachusetts Democrat decided against making the trip after suffering a seizure last Saturday and undergoing a brain biopsy on Monday. A malignant brain tumor was diagnosed on Tuesday.

Obama, who leads in the race for the Democratic presidential nomination, said he and Kennedy had talked earlier in the week about the Illinois senator delivering the speech. Kennedy has endorsed Obama in his race against fellow Democrat Hillary Rodham Clinton (web|news|bio) and has campaigned for Obama.

"Considering what he's done for me and for our country, there's nothing I wouldn't do for him," Obama said in a statement. "So I'm looking forward to standing in his place on Sunday, even though I know I won't be able to fill his shoes."

Spokeswoman Stephanie Cutter said Kennedy accepted Obama's offer to help "knowing it would be an historic opportunity for the school and all those attending. ... He's enormously grateful to Sen. Obama and the support he's received from all of his colleagues this last week."

Kennedy will not attend the graduation ceremonies, remaining at his family compound on Cape Cod. He returned to Hyannis Port on Wednesday after being released from Massachusetts General Hospital.

The senator will still keep long-standing plans to host Raclin, daughter of his wife, Vicki, at a dinner Saturday night. Also expected at the dinner are her siblings, grandparents and aunts and uncles.

Congress is on a Memorial Day recess next week, although it is unclear when Kennedy will return to Capitol Hill. His doctors are weighing chemotherapy and radiation regimens, but no further announcement is expected from them before midweek.