Hillary Clinton appears with Bernie Sanders at a rally in July in Portsmouth, N.H. (Melina Mara/The Washington Post)

Bernie Sanders, the runner-up for the Democratic presidential nomination, said Sunday that the threshold should probably be lower for third-party candidates like Libertarian Gary Johnson to take part in the fall debates.

Sanders, an independent senator from Vermont, was asked about the current 15 percent polling threshold during an appearance on NBC’s “Meet the Press.”

“Probably too high,” said Sanders, who is set to return to the campaign trail Monday in New Hampshire on behalf of Democratic nominee Hillary Clinton.

Johnson, a former governor of New Mexico, has reached double digits in some national polls but does not appear likely to clear the bar of 15 percent set as a participation requirement by the Commission on Presidential Debates. The commission looks at an average of recent polls to make a determination.

Green Party candidate Jill Stein is likely to fall well short of meeting the participation requirements before the first of three debates between Clinton and Republican nominee Donald Trump, scheduled for Sept. 26 at Hofstra University in Hempstead, N.Y.

The commission also requires candidates to be on ballots in enough states to have a mathematical chance of winning the presidency.

During his “Meet the Press” appearance, Sanders did not suggest a different polling figure to qualify for the general-election debates but said it “probably should be lower” than 15 percent.

The standard has been in place since 2000. On its web site, the commission says its judgment was that “the 15 percent threshold best balanced the goal of being sufficiently inclusive to invite those candidates considered to be among the leading candidates, without being so inclusive that invitations would be extended to candidates with only very modest levels of public support, thereby jeopardizing the voter education purposes of the debates.”

Sanders also told host Chuck Todd that he thinks that Clinton, if elected president, “should cease all operations, all contact with the Clinton Foundation.”

Sanders stopped short of saying that the charitable foundation itself should be shut down, citing “a lot of good work” that it does fighting AIDS around the globe.

The foundation, which has been a project of Clinton, her husband and her daughter, has said that it will cease taking foreign and corporate donations if she reaches the White House. Even some Democratic allies of Clinton have suggested that those steps should be taken now.