The DNC has finally broken my ability to give

[progressoid]

46. But there are dozens of ways your number gets shared. Actblue notwithstanding.

Candidates and parties can easily get your voting information directly from the state. And depending on the state in which you live, that can include phone numbers and email addresses. I have a couple friends who have run for office. One of the first things they do is pay for the data base of all registered voters.
https://www.ncsl.org/elections-and-campaigns/access-to-and-use-of-voter-registration-lists

Then there are previously mentioned sharing from candidates. As the EFF states:

Campaigns also share information about you with other campaigns, so if you register with a candidate one year, it's likely that information goes to another in the future. For example, the website for Adam’s Schiff’s campaign to serve as U.S. Senator from California has a privacy policy with this line under “Sharing of Information”:

With organizations, candidates, campaigns, groups, or causes that we believe have similar political viewpoints, principles, or objectives or share similar goals and with organizations that facilitate communications and information sharing among such groups

Similar language can be found on other campaign sites, including those for Elizabeth Warren and Ted Cruz. These candidate lists are valuable, and are often shared within the national party. In 2017, the Hillary Clinton campaign gave its email list to the Democratic National Committee, a contribution valued at $3.5 million.

https://www.eff.org/deeplinks/2024/04/how-political-campaigns-use-your-data-target-you

If you want to go through a data broker, Target Smart claims to have 171 million accurate phone numbers for sale. https://targetsmart.com/data-solutions/

If you are, lets say less than scrupulous, there are plenty of dark web sources to get info for spamming.

Etc., etc., etc.