It's no so much what you should do now but what you should have done when selecting your major.

My suggestion would be to enroll in a community college and start taking all the courses - and earn all the certificates - you can that relate to marketing because no one with only your present credentials is likely to find a marketing job.

"... Bachelor’s degree in Political Science and International Relations", this background might help you get a foot in the door of political management & marketing. You might have to start out doing volunteer work in telemarketing, direct mail, event planning etc. Then over time, you could develop a marketing project proposal for a fee. Gaining a good reputation in political branding and marketing will also create a personal brand, your branding plan for you.

And as Phil suggests, it's a good idea to continue your education by taking marketing classes.

Unless you get extremely lucky, you're going to have to learn the nuts and bolts of the career you want before anyone will hire you to perform. That probably means going back to school for an MBA or other graduate degree in the field you want to pursue.

You can start by reading some books on Marketing, and you can do some volunteer work, take a few courses, etc. But sooner or later you need to demonstrate that you're committed to your career and have the basic knowledge and skills to be successful. My sense is that you'll do best by getting an MBA degree.

No shortcuts or free lunches, I'm afraid. Just be very sure this is what you want before you invest a lot of time, effort, money and emotional energy in the process.

A prospective employer needs to know what you bring to the table and how your skills can benefit them. Success lies in aligning your skills (and what you can do) with the desires of the company you're looking to work for.

No one in education teaches this simple, fundamental truth because it's TOO simple, and because it's TOO obvious.

My co-contributors have given you valuable advice: heed it.