(CNN) The Democratic National Committee plans to meet with 2020 campaigns next week to hand out an "affirmation form" for candidates to sign and certify they will run and serve as members of the Democratic Party, a DNC official said Tuesday.

The announcement follows Bernie Sanders' entry into the 2020 campaign earlier Tuesday — his second consecutive presidential election. An independent who caucuses with Democrats in the Senate, Sanders rankled some Democrats in 2016 when he ran for the nomination even though he wasn't an official member of the party.

DNC members passed a new rule last August, which was seen as a response to the Sanders campaign, requiring all candidates "to affirm in writing" that they "are a member of the Democratic Party, will accept the Democratic nomination; will run and serve as a member of the Democratic Party."

According to the DNC, all the campaigns who have announced have been invited to the meeting. Once they receive the form, they will have a week to return it to the DNC.

"The DNC will present presidential campaigns that have currently announced their candidacy or the creation of an exploratory committee, with the rules and other materials next week at a briefing and this will include the candidate affirmation form," the official said. "As any additional candidates enter the race, they will be provided with the same information and will be required to return the form in the same time frame."

The Sanders campaign didn't immediately respond to say whether the senator would sign the form.

Sanders officially jumped into the 2020 race with stronger party support than he had four years ago. Both Democratic members of his state's congressional delegation, Sen. Pat Leahy and Rep. Pete Welch, endorsed him. According to a campaign official, Sanders has already raised more than $3 million dollars since the morning announcement.