At a birthday bash Sunday evening celebrating Hillary Rodham Clinton's 68th birthday, the stars were out, with a performance by John Legend. A gaggle of New York celebrities has supported Clinton's presidential run, from Robert De Niro to Lena Dunham to Jennifer Lopez.

"Hillary's paid her dues," De Niro has said, "and has earned the right to be president."

But do celebrity endorsements help? According to a study by University of Maryland economists, Oprah Winfrey's 2008 endorsement of Barack Obama boosted his campaign contributions and his total vote by more than 1 million.

An endorsement by someone like Winfrey can work wonders. But other celebrity salutes? Not so much.

Photos and words of support from the Duggar family of TV's "19 Kids and Counting" vanished from GOP presidential candidate Mike Huckabee's website after reports that Josh Duggar molested underage girls, including his sisters.

GOP contender Sen. Marco Rubio has received a lusty endorsement from retired porn star Jenna Jameson, who called him "the clear choice" for president. Jameson, who backed Clinton in 2008 and Mitt Romney in 2012, explained her rightward drift by saying, "When you're rich, you want a Republican in office."

Will Rubio get a Jameson bump? Stay tuned.

Meanwhile, one of rapper Lil B's songs includes the lyrics "Shout out to Hillary Clinton, you gonna win that presidency, you gonna be president soon, baby!" But he startled Clinton by switching his allegiance to Sen. Bernie Sanders, tweeting, "As much as I want a woman leading the USA, right now it's all about Bernie. I heard he marched against segregation in the '60s . . . I love that brave dude!"

Is anyone impressed with the caliber of celebs supporting Donald Trump? Perhaps. The Donald's list of celebrity endorsements includes rock singer and gun nut Ted Nugent as well as ex-basketball star Dennis Rodman, buddy of psycho North Korean dictator Kim Jong Un ("Lil' Kim").

Finally, singer Kid Rock told Fox News' Megyn Kelly that he likes "the black guy." Kelly asked whether he could be specific. "Ben Carson. That guy makes a whole lot of sense."

Whatever you say, Kid.