WASHINGTON — Sen. Edward M. Kennedy will be a tough act to follow, even for the Kennedys. His death, coupled with the decision by family members not to seek the seat he held for nearly five decades, has prompted predictions that the family's political dynasty is over.

There's talk the Kennedy political bloodlines are running thin. Some say the younger brood lacks the grit and zest for political combat that drove the liberal Democrat to become one of the leading politicians of the last 40 years.

Yet it's probably too early to write off one of America's most powerful and popular families. A new generation of Kennedys could emerge to extend the dynasty.

Stephen Hess, author of “America's Political Dynasties,” said such dynasties often ebb and flow. And while no obvious successors to the late senator are apparent, there is a pool of about two dozen Kennedy cousins.

“That name, or that legacy, is going to inspire some of them to go into elective politics, particularly since it obviously gives them an advantage,” said Hess.

He noted that in the 1960s, few were predicting Ted Kennedy would become the family's standard-bearer after his two older brothers, John, the president, and Robert, the former attorney general-turned-senator, were slain.

Some Democrats hope the late senator's eldest son, Edward Kennedy Jr., steps up. The Connecticut attorney, 48, said he's considering following in his father's footsteps, but has no immediate plans to do so. He has two children, ages 11 and 15.

Kennedy, who lost a leg to cancer at age 12, founded an investment firm, the Marwood Group, in New York City and is an advocate for the disabled.

Former six-term Massachusetts representative Joe Kennedy, 57, the eldest son of Robert Kennedy, chose not to run for his uncle's Senate seat. His congressional background and his work running Citizens Energy Corp., which provides discounted heating oil to low-income families, could help if he returns to politics.

There's also been speculation that one of Joe Kennedy's two sons, Joseph Kennedy III, could seek his father's old House seat if the current holder, Rep. Michael Capuano, wins the special election to replace Ted Kennedy in Massachusetts.

Kathleen Kennedy Townsend, the eldest of Robert Kennedy's 11 children, was lieutenant governor of Maryland, but her 2002 gubernatorial bid sputtered.