DETROIT - Joe Biden rarely lets a public event pass without reminding voters of his work alongside U.S. President Barack Obama, but the former vice-president insists he's not overly relying on that relationship to fuel his 2020 White House bid.

At a forum Wednesday in Detroit sponsored by the NAACP, Biden said, "It's not a crutch." He says, "You can ask President Obama. I don't need any crutch."

The comment reflects the challenge facing Biden as he tries to protect his fragile status as the early Democratic front-runner.

His frequent invocation of the Obama years could appeal to Democrats, particularly African Americans, who hold the former president in high regard.

But presidential candidates are rarely successful if they're viewed as simply the next chapter of a prior administration.