Can my employer fire me for voting for Barack Obama (or for wearing an Obama tee shirt)?
No. In Connecticut, we have a statute that applies the protections of the First Amendment to private employers. Without this statute, the First Amendment would only protect government employees.
Section 31-51q of the Connecticut General Statutes provides:
Any employer, including the state and any instrumentality or political subdivision thereof, who subjects any employee to discipline or discharge on account of the exercise by such employee of rights guaranteed by the first amendment to the United States Constitution or section 3, 4 or 14 of article first of the Constitution of the state, provided such activity does not substantially or materially interfere with the employee’s bona fide job performance or the working relationship between the employee and the employer, shall be liable to such employee for damages caused by such discipline or discharge, including punitive damages, and for reasonable attorney’s fees as part of the costs of any such action for damages. If the court determines that such action for damages was brought without substantial justification, the court may award costs and reasonable attorney’s fees to the employer.
The general idea is that you are allowed to engage in protected First Amendment speech, which usually means that it has to be speech on matters of public concern (supporting Senator Obama definitely qualifies!) and the manner in which you express yourself cannot disrupt the workplace.
It is probably a good idea to check to see if your employer has any specific dress codes or other policies which address this issue before you express yourself at work.