An independent candidate for president, Robert F. Kennedy Jr., is heading to Arizona on Wednesday to rally against state laws that make it difficult for independent and third-party candidates to get on the ballot. Meanwhile, Senator Manchin is pouring cold water on the idea of a third-party run.

Mr. Kennedy is due at Phoenix this week as he aims to drum up support for his White House bid in the key swing state. 

“Normally, independent candidates pay companies millions of dollars to gather signatures,” Mr. Kennedy said in a statement. “We’re taking a different route that starts with our thousands of volunteers in every state.”

In Arizona, independent candidates for the presidency are required to get signatures equal to 3 percent of the state’s registered voters. Although the requirement will be based on voter registration at the beginning of 2024, the state estimates it is home to about 4.2 million registered voters in the state.

This means that Mr. Kennedy’s campaign will need somewhere upward of 125,000 signatures to appear on the ballot in Arizona, and this is just one of 50 states.

In a post on Substack, Mr. Kennedy complained that other states have even stricter rules on signature collection, like Texas, which requires that independent candidates collect more than 113,000 signatures in fewer than 11 weeks.

“A campaign should not have to devote its money, time, and energy to ballot access, but rather to speaking to voters to win their support,” Mr. Kennedy wrote. “The current system amounts to deliberate and arbitrary suppression of the democratic process.”

Although year-out polling is not predictive of an election’s outcome, Mr. Kennedy appears to be the most popular independent or third-party candidate nationally at the moment.

A recent survey from Harris X and Harvard found that Mr. Kennedy enjoys 20 percent support in a matchup that also features Presidents Biden and Trump.

As Mr. Kennedy gets ready to rail against ballot access laws, one prominent potential third-party candidate, Mr. Manchin, is pouring cold water on the prospects of a presidential bid.

Mr. Manchin has been floated as a prospective candidate for the self-fashioned nonpartisan group No Labels, which has said it is planning on putting up a candidate should 2024 end up being a rematch of the 2020 election.

On CNN’s “State of the Union,” though, Mr. Manchin said that there was “no timeline” for a potential decision on whether he will run for president. 

“I haven’t said I’m going to run for president. I have said that basically, this country doesn’t work from the extremes,” Mr. Manchin said. “You can’t weaponize our system to make thinking that anybody on the other side that you’re not on is your enemy, and you treat them as an enemy.”

When he announced that he would not seek another term in the Senate, Mr. Manchin said that he planned to tour the country “to see if there is an interest in creating a movement to mobilize the middle,” stoking speculation that the tour would result in a bid with No Labels.

Mr. Manchin has since appeared to back off from exploring a third-party run for fears of spoiling the election and hindering Mr. Biden’s chances of re-election.