WASHINGTON (AP) — Ben Carson is trying to reinvigorate his campaign for Republican presidential nomination by becoming the latest to question Barack Obama's blackness ahead of critical upcoming votes.

The retired neurosurgeon, hovering near the bottom of the GOP field, said in a series of recent interviews that Obama was "raised white" and doesn't represent the "black experience" in the United States.

"He didn't grow up like I grew up," Carson, the only black major party candidate in the 2016 presidential race, said on MSNBC. "Many of his formative years were spent in Indonesia. So, for him to, you know, claim that, you know, he identifies with the experience of black Americans, I think, is a bit of a stretch."

He also told Politico's "Off Message" podcast released Tuesday that the president was "raised white."

Carson has come under racial criticism himself, but his comments helped him break through the cacophony of speeches and interviews by provocative front runner Donald Trump and rivals Ted Cruz, Marco Rubio and John Kasich. Carson came in near the bottom in last week's GOP primary in South Carolina, and faces a struggle in the Super Tuesday primaries March 1.

Carson's "lashing out. His campaign is on its last leg," said Leah Wright Rigueur, a professor of public policy at Harvard University's Kennedy School of Government. "Here's a chance for him to reinsert himself into the national conversation and rile up the base."

"His comments are not geared toward black audiences; they're geared toward white conservatives," Rigueur added.

Carson has leveled race-based attacks before, saying in 2013 "Obamacare is the worst thing that has happened in this nation since slavery." And he's suggested he is still waiting to see evidence of racial bias by U.S. law enforcement agencies.

But even as Carson questions Obama's "blackness," he's complaining about being politically and racially typecast. While Obama, once a curiosity because his mother was white and his father was black, has been fully embraced by many black Americans as one of their own. Carson, however, has lost some admiration that many blacks held for his life story and medical accomplishments as his conservative views won praise in heavily white Republican circles.

"They assume because you're black, you have to think a certain way," Carson said in the Politico interview. "And if you don't think that way, you're 'Uncle Tom,' you're worthy of every horrible epithet they can come up with; whereas, if I weren't black, then I would just be a Republican."

Angela Johnson Meadows, who worked for Diversity Best Practices, an organization that promotes diversity, says that view combined with Carson's comments on Obama are "ironic and a bit hypocritical."

Meadows defined a black experience as something that can happen to a black person, or to someone who identifies as black. For example, she said, many blacks have roots in the South, are church-going, love soul food, and other things that make up a "black experience" — but those things alone do not define blackness, she said.

"I don't think that if you don't experience those things you are not black or not living a black experience," she said.

Carson not the first to level "blackness" criticism at Obama.

In a 2011 interview on MSNBC's "The Ed Show," longtime critic Cornel West said Obama, as the son of an African father and a white mother, "always had to fear being a white man with black skin. ... All he has known culturally is white."

Similarly, media magnate Rupert Murdoch said on Twitter in October: "Ben and Candy Carson terrific. What about a real black president who can properly address the racial divide? And much else," Murdoch tweeted. He later apologized.

Carson's criticisms are aimed at winning white conservatives voting in upcoming contests, experts said.

"He's lost whatever stakes and resonance he had in black America with his previous achievements by the blight of his GOP campaign," said Georgetown University professor Michael Eric Dyson, adding that Carson "has outright attacked black people in some instances," been critical of black culture and "strategically de-emphasized" racial identity as a necessity.