By Jason Szep

BOSTON (Reuters) - As U.S. Sen. Edward Kennedy battles a deadly brain tumour, many Americans hope his illness will not bring a swift end to the Kennedy political era.

Kennedy, 76, the last of four brothers in America's most storied political dynasty, was released from hospital on Wednesday, four days after suffering a seizure at his family vacation home on Cape Cod on Saturday.

"There seems to be no one there to pick up the torch," said Thomas Whalen, a professor of politics at Boston University.

"There doesn't seem to be someone in the next generation to carry the load here -- Ted Kennedy might be it, he might be the end of the line," said Whalen, author of "Kennedy versus Lodge: The 1952 Massachusetts Senate Race" about his brother John's first race for the Senate.

Massachusetts, a bastion of the type of liberal politics Kennedy championed for four decades, has been stunned by the Democratic senator's diagnosis of glioma, a type of tumour that kills half its victims within a year.

"Everyone has to take a deep breath," said Jeffrey Berry, a political science professor at Tufts University in Medford, Massachusetts. "There will be no pressure on him to step down even if he becomes quite ill from treatment."

"Nobody is going to be in a rush to replace him with a new senator who starts at the bottom of the seniority chain."

It is unclear whether Kennedy will have to resign because of his illness, but he may take time off from the Senate while undergoing chemotherapy.