SIOUX FALLS, S.D. — Sen. Hillary Rodham Clinton quickly apologized yesterday after citing the June 1968 assassination of Robert F. Kennedy as a reason to remain in the race for the Democratic presidential nomination despite increasingly long odds.

"I regret that if my referencing that moment of trauma for our entire nation and in particular the Kennedy family was in any way offensive. I certainly had no intention of that whatsoever," the former first lady said.

The episode occurred as Clinton campaigned in advance of the June 3 South Dakota primary.

Responding to a question from the Sioux Falls Argus Leader editorial board about calls for her to drop out of the race, 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? We all remember Bobby Kennedy was assassinated in June in California. You know, I just, I don't understand it," she said, dismissing the idea of abandoning the race.

Clinton said she didn't understand why, given this history, some Democrats were calling for her to quit.

Her remark about an assassination during a primary campaign drew a quick response from aides to Democratic presidential front-runner Barack Obama.

"Senator Clinton's statement before the Argus Leader editorial board was unfortunate and has no place in this campaign," said Obama spokesman Bill Burton.

Clinton spokesman Mo Elleithee said the senator was only referring to her husband and Kennedy "as historical examples of the nominating process going well into the summer and any reading into it beyond that would be inaccurate and outrageous."

MCCAIN APPEARS IN GOOD SHAPE

WASHINGTON — Doctors for John McCain gave the 71-year-old likely GOP presidential nominee a clean bill of health yesterday, but refused to discuss the various medical issues he can be expected to face over the next four years.

McCain's most apparent health risk is skin cancer, his doctors indicated as they discussed the removal of his four malignant melanomas and other less serious skin cancers. The most serious was an "invasive" melanoma on his lower left temple that required extensive surgery in August 2000.

But the doctors, in a conference call with reporters arranged by McCain's campaign, said they found no recurrence of that melanoma since then.

That fact, his dermatologist Dr. Suzanne Connolly said, makes his prognosis look good, though he remains at risk and must protect himself from sun.

"Senator McCain enjoys excellent health and displays extraordinary energy," said Dr. John Eckstein, an internist and McCain's personal physician.

"While it is impossible to predict any person's future health," Eckstein added, "today I can find no medical reason or problems that would preclude Senator McCain from fulfilling all the duties and obligations of president of the United States."

McCain invited select national media to review 1,173 pages of medical documents dating from late 1999 to this year. Journalists could study the stacks for three hours, but campaign officials prohibited photocopies. Staffers quickly collected the materials as soon as the allotted time expired. His doctors subsequently participated in a telephone news conference.

OBAMA COURTS CUBAN-AMERICANS

MIAMI — Sen. Barack Obama, who once said he would meet Cuban leader Raul Castro without preconditions, added yesterday he would do so "only when we have an opportunity to advance the interests of the United States and to advance the cause of freedom for the Cuban people."

Any meeting would occur "at a time and place of my choosing," the likely Democratic presidential nominee told an audience of Cuban-Americans who applauded his remarks.

Obama said he would maintain the existing trade embargo to use as leverage for winning democratic change in the Communist island nation. But he said he would immediately allow "unlimited family travel and remittances to the island."

"It's time to let Cuban-Americans see their mothers and fathers, their sisters and brothers. It's time to let Cuban-American money make their families less dependent upon the Castro regime," he said.

Obama made his remarks as part of his first extended trip through swing-state Florida, beginning a courtship that ordinarily would have occurred much earlier in the year. But the state's Jan. 29 primary date violated Democratic National Committee rules, and the party's presidential hopefuls observed a ban on campaigning.

CINDY MCCAIN MADE $6M IN '06

WASHINGTON — Call Cindy McCain the Six Million Dollar Woman.

McCain, the wife of Arizona Sen. John McCain, the presumptive Republican presidential nominee, earned more than $6 million in 2006, according to tax returns the McCain campaign released yesterday.

Cindy McCain is the chairwoman of Hensley Co., an Arizona beer distributorship founded by her father in 1955.

In 2007, the privately held firm, the nation's third-largest Anheuser-Busch distributorship, sold 23 million cases of beer, according to the company's Web site.

She earned $6,066,431 in 2006, of which $5,496,694 was taxable income.

She paid taxes of $2,042,564 and received a tax refund of $296,119.

The McCains, married for 28 years, keep their finances separate and file tax returns separately under a prenuptial agreement.

The McCain campaign released John McCain's tax returns for 2006 and 2007 last month but had refused to release Cindy McCain's returns. Speaking on NBC's "Today Show" on May 8, Cindy McCain said she would never release her tax returns, even as first lady, because "it's a privacy issue. ... I'm not the candidate."

Her husband's campaign offered no explanation for her change of heart.

The campaign released only the first two pages of Cindy McCain's 1040 form from one year: 2006. She received an extension on filing her 2007 tax returns.