Robert F. Kennedy Jr. has declared that he will run in next year's US presidential election as an independent candidate.

The lawyer and nephew of former President John F. Kennedy announced his bid in Pennsylvania on Monday.

He had been campaigning for the Democratic Party nomination since April, but says he's dropping out of the primary race.

Kennedy said in his speech that the favorability ratings of both President Joe Biden and former President Donald Trump are in deep negative territory. "That's what two-party politics has given us," he said.

Kennedy said, "We declare independence from the two political parties."

Analysts say Kennedy could take votes away from both the Democratic and Republican camps.

As the son of former Attorney General Robert F. Kennedy, he is well-known as a member of the Kennedy family. And his hardline stance against the coronavirus vaccine has also earned him a measure of Republican support.

Earlier this month, a Reuters/Ipsos poll of a hypothetical three-way race between Biden, Trump and Kennedy showed Kennedy winning 14 percent of likely voters.