Tonight in Maine, US Senator Bernie Sanders kicks off a multi-stop national tour with the recently-elected DNC chairman, Tom Perez. The appearances are aimed at corralling Sanders' supporters to back new party leadership, but the tour comes with a catch: Sanders will keep the website data he collects.

On Sunday Hillary Clinton's campaign donated her email list, including data on donors and supporters, to the Democratic National Committee. Both the DNC and Clinton’s campaign said this included 10 million people that the DNC did not have previously in its database. It was an in-kind contribution, valued at $3.5 million.


Those who want to attend can RSVP at one of two places -- via Sanders' website or through the DNC. Josh Miller-Lewis, a Sanders aide, confirmed that while each group keeps the data collected on their respective websites, any information collected at the event will be shared. And at each website, supporters can give their name, email address, and zip code.

In modern campaigns, this kind of data is more important than money. Parties and candidates can raise money from these e-mail lists via direct solicitation or renting them out. This data makes it easy to spread a certain message, allowing campaigns to do direct outreach to like-minded voters or build an audience for future events.

During the campaign, Clinton pledged to help rebuild the Democratic Party, which slipped structurally while former president Barack Obama was in office. During the Obama administration, the party lost nearly a 1,000 state house seats around the country, control of the US House, US Senate, and the presidency.

By giving her data to the DNC, Clinton is not only keeping her promise to help the party, but also she is signaling that she might really be done with politics and therefore has no more use for this valuable information.


Sanders, on the other hand, has not given any of his data over to the DNC. But given how his campaign was treated by the DNC in the 2016 campaign (as documented by Wikileaks), it's hard to blame him for hard feelings. (Sanders' supporters have previously argued they should not hand over their data.)

Yet the fact remains that while Sanders might be asking Mainers to go all in and help the DNC, he is still keeping himself somewhat separated from the party.

James Pindell can be reached at james.pindell@globe.com. Follow him on Twitter @jamespindell or subscribe to his Ground Game newsletter on politics: http://pages.email.bostonglobe.com/GroundGameSignUp