Whoever corruptly, or by threats or force, or by any threatening letter or communication, endeavors to influence, intimidate, or impede any grand or petit juror, or officer in or of any court of the United States, or officer who may be serving at any examination or other proceeding before any United States magistrate judge or other committing magistrate, in the discharge of his duty, or injures any such grand or petit juror in his person or property on account of any verdict or indictment assented to by him, or on account of his being or having been such juror, or injures any such officer, magistrate judge, or other committing magistrate in his person or property on account of the performance of his official duties, or corruptly or by threats or force, or by any threatening letter or communication, influences, obstructs, or impedes, or endeavors to influence, obstruct, or impede, the due administration of justice, shall be punished as provided in subsection (b). If the offense under this section occurs in connection with a trial of a criminal case, and the act in violation of this section involves the threat of physical force or physical force, the maximum term of imprisonment which may be imposed for the offense shall be the higher of that otherwise provided by law or the maximum term that could have been imposed for any offense charged in such case.