You can be cordial. Cordial is non-commital, changes the subject when the awkward and contriverisal is raised. Cordial does not particularly like the person, but embraces the situation or the holiday and stands above the pettiness of disagreements.
If “pettiness of disagreement” is how you define voting for Obama, you are totally clueless as to the dire situation the nation is in. Totally.
Tootalu.