Well, there two are VTiger and SugarCRM. Look at those to start.
SugarCRM is one I tried out a few years ago. The database portion was a bit cumbersome for a single-user environment.
Either could do well, especially if you have a server environment.
Take a look at this one, "SplendedCRM". It is built on Microsoft's environment, so it's a bit easier to host on a personal computer.
What are you looking for the software to do? If it's an interesting enough project, I might be willing to undertake it to hone my Java skills.
If you need the data converted from some other format into whatever you choose, that's what I do. I wouldn't mind putting in a few hours for the cause.
Freep mail me if interested.
In the GOP, one of the more popular choices for campaign management software was from Hannibal Software. I don't know if they're still in business, but they do charge for their products.
The Federal Election Commission lists several other commercial solution providers here