When Bernie Sanders announced his presidential candidacy earlier this week, he verbally reaffirmed his commitment to the Democratic Party, despite being an independent.Now, he will take it a step further and will put it in writing.Sanders' campaign confirmed Friday that he will sign a formal “affirmation” pledge to comply with Democratic National Committee rules passed last summer requiring all candidates for the party’s presidential nomination to state their commitment to the party. The new rules were clearly aimed at Sanders, responding to concerns voiced about his decisions to decline the nomination of the Democratic Party in Vermont in his U.S. Senate races in 2006, 2012 and 2018.While Sanders is an independent, he does caucus with the Democratic senators. But he designates himself as "Sen. Bernie Sanders, I-Vermont" in news releases and on his official Senate website.In 2016, Sanders filed for the New Hampshire primary as a Democrat. His filing was challenged, but the state Ballot Law Commission upheld his eligibility to appear on the Democratic primary ballot. That ruling was made despite a requirement in state law that a candidate declare that he or she is a “registered member” of the party in which he or she chooses to run for president.In response, New Hampshire lawmakers are currently considering a bill that would relax the filing requirement to allow a “recognized candidate for the president in the party in which I desire to file” on the ballot, regardless of whether the candidate is a registered member of the party.Vermont has open registrations, without specific party registrations for voters. Voters can choose to vote in either Democratic or Republican primaries.Supporting the new New Hampshire bill, Ballot Law Commission Chairman Bradford Cook told state lawmakers at a hearing in January, "The Ballot Law Commission, interpreting the statute as it currently reads, would be required, because it's our job to apply your laws, to keep him off the ballot."A House committee has recommended on a unanimous, bipartisan basis that the full House pass the bill.On the national level, the Democratic National Committee, formulating its rules after the divisive 2016 nomination battle between Sanders and Hillary Clinton, included a new rule that addresses questions about Sanders’ allegiance to the party.According to the DNC, a candidate for the 2020 Democratic presidential nomination, must under a rule, "be a bona fide Democrat whose record of public service, accomplishment, public writings, and/or public statements affirmatively demonstrates that the candidate is faithful to the interests, welfare, and success of the Democratic Party of the United States who subscribes to the substance, intent, and principles of the Charter and the Bylaws of the Democratic Party of the United States, and who will participate in the Convention in good faith."Under a separate new rule, the candidate must also publicly affirm that he or she is a Democrat, the DNC said. As part of that requirement, they must affirm in writing to the chair of the DNC that they "are a member of the Democratic Party; will accept the Democratic nomination; and will run and serve as a member of the Democratic Party."The DNC told WMUR it will present presidential campaigns that have so far announced their candidacies or the creation of an exploratory committee with the rules and other materials next week at a briefing -- and the “candidate affirmation form” will be included.“Candidates who have officially announced their candidacy will have a week to return a signed copy of the affirmation form to the DNC. 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 DNC said.A spokesperson for Sanders’ campaign confirmed Friday that Sanders will make the required written affirmation. Whether he will change his Senate designation to "D-Vermont" is not clear. Earlier this week, Sanders told WMUR, “I’ve been running all over this country to elect Democrats to the U.S. House, to the U.S. Senate and governors. I have raised millions of dollars for Democratic candidates.”“I think I’ve paid my dues and I have shown the world that I am an active member of the Democratic leadership in the U.S. Senate.”But he also said that there are independents and across the country “who are concerned about both political parties and they become either independents or not connected to Democrats or Republicans.“It is important that we reach out to those people, who are often young people and often people of color and tell them that we have a Democratic Party now that is prepared to stand up for working people,” Sanders said.