Then you're misguided and misinformed. In the US, we never take oaths to any individual, team or side, but the nation as a whole and it's guiding principles.
I do solemnly swear (or affirm) that I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God.
In addition members of the judiciary take the following oath.
I, (name), do solemnly swear (or affirm) that I will administer justice without respect to persons, and do equal right to the poor and to the rich, and that I will faithfully and impartially discharge and perform all the duties incumbent upon me as (office) under the Constitution and laws of the United States. [So help me God.
Asking otherwise is un-American.