As an incoming Poli Sci PhD student whose wife is a social worker, I feel like I can answer this with *some* level of expertise. I majored in English, so I know for a fact that even at a mid-to-upper-tier school, your undergrad major doesn't HAVE to be Poli Sci. I would give these caveats, though:
1. I would hope that your minor was Poli Sci, or at least some kind of social science. If not, you're going to struggle.
2. The typical warning...if you can't get into a Top 25 program, DON'T ATTEMPT A PHD. If you're not familiar with why, then you're not ready for the crucible of applications, and you're CERTAINLY not ready to spend five years of your life in grad school.
3. I will try to say this gently...as someone who loves a social worker, and as someone who is well-acquainted with the world of social work and social workers, I can tell you that social work is not an intellectually rigorous field. This is not to say that social workers aren't smart, but...a lot of social workers aren't exactly rocket scientists, and the field doesn't expect them to be. They are expected to be compassionate and hard-working. I have helped three people get into Social Work Master's programs in the past couple of years (as I said, I have a BA in English, so I'm expected to proofread all my friends' work). None of them had the writing ability or the GRE scores to even be considered for a Poli Sci PhD. They were all accepted into the Social Work program, which is the top program in my state...some with advanced standing.
I only tell you all of this so you know what you're up against. Being published is a huge advantage over your typical social worker, but if I were running an upper-tier program, I'd have to see some kind of advanced mathematics (super-high GRE scores, too) or a social sciences minor at an elite undergrad school before I'd consider anyone from a social worker's background. If I were in your shoes, unless I ate, drank, slept, and breathed political science, I'd look elsewhere. Since you're used to more practical, real-world applications to your coursework, I might look into a Master's in Poli Sci. Those are more professional-based degrees and they have a lower barrier to entry.