Members of the Kennedy family are incensed over Hillary Rodham Clinton‘s invoking the assassination of Robert F. Kennedy to explain why she’s staying in the race – and they think it could be the death knell of an increasingly desperate and sloppy campaign.

“That comment may be the last nail in her campaign’s coffin,” a Kennedy relative told The Post. “How can Hillary even use the experience argument when she repeatedly pushes the wrong buttons in her comments?”

An insider added, “I think people really felt that a line was crossed and that her campaign – and even her legitimacy as a politician – ended today.”

Said a second relative, “She no longer has only her husband to blame for the ill-chosen comments coming from her camp.”

While Robert Kennedy Jr. immediately came out in support of Sen. Clinton on Friday, others in the family’s inner circle are fuming.

One cited “a perceived insensitivity” in her comment, made Friday before a South Dakota newspaper’s editorial board, especially with the 40th anniversary of RFK’s death two weeks away and Sen. Ted Kennedy battling a brain tumor.

“We were all sort of dumbfounded that she would say such a thing,” the insider said.

There was also anger outside the family. The Rev. Al Sharpton ripped the comment as dangerous.

The Kennedy family insider added: “I know that many Clinton supporters in New York and New Jersey are sickened by her comments and that they are more concerned with Senator Kennedy’s health and well-being than they are her campaign anymore.

Clinton was explaining why she was still in the race against Sen. Barack Obama when she said: “My husband did not wrap up the nomination in 1992 until he won the California primary somewhere in the middle of June. Right?”

Then she added: “We all remember Bobby Kennedy was assassinated in June in California.”

That line, which she later said was meant to convey the fact that nomination battles can extend late into the primary season, also sparked outrage for touching upon Obama’s personal safety.

It was also just plain inaccurate, say historians, noting that Clinton’s drawn-out battle with Obama in a seemingly endless primary season is nothing like the 1968 and 1992 Democratic campaigns.

Bobby Kennedy was not in the midst of a long-fought primary battle when he was assassinated. He entered the race on March 16, 1968, less than three months before the June 5 shooting.

As for Bill Clinton, despite his wife’s perceptions, he’d won the nomination long before mid-June 1992. The race was essentially over by March 20, when Paul Tsongas dropped out and Clinton became the front-runner with a 7-to-1 delegate lead over Jerry Brown.

Obama, meanwhile, plans to give the commencement speech at Wesleyan University’s graduation today in Connecticut, replacing the ailing Ted Kennedy.

Obama will be greeted by an unprecedented amount of security. The ceremony will be closed to the public, and guests will have to go through metal detectors.

One presidential historian thinks Clinton’s loose-lipped reference to assassination raises the danger of someone’s targeting Obama.

“Everybody, in the back of their minds, has been thinking of this, that Senator Obama could be in danger,” said Rick Shenkman, a professor at George Mason University in Virginia.

“Now it’s out there. It only takes one psycho.”

In a radio interview yesterday in Puerto Rico, Obama said that he had accepted the apology Clinton issued Friday and that her comment about RFK was just “careless.”

Additional reporting by Charles Hurt

geoff.earle@nypost.com