SEC. 2021. Whenever an election at which Representatives or Delegates in Congress are to be chosen is held in any city or town of 20,000 inhabitants or upward, the marshal for the district in which the city or town is situated shall, on the application in writing of at least two citizens residing in such city or town, appoint special deputy marshals, whose duty it shall be, when required thereto, to aid and assist the supervisors of election in the verification of any list of persons who may have registered or voted; to attend in each election district or voting precinct at the times and places fixed for the registration of voters, and at all times or places when and where the registration may by law be scrutinized and the names of registered voters be marked for challenge; and also to attend, at all times for holding elections, the polls in such district or precinct. SEC. 2022. The marshal and his general deputies, and such special deputies, shall keep the peace and support and protect the supervisors of election in the discharge of their duties, preserve order at such places of registration and at such polls, prevent fraudulent registration and fraudulent voting thereat, or fraudulent conduct on the part of any officer of election, and immediately, either at the place of registration or polling place, or elsewhere, and either before or after registering or voting, to arrest and take into custody, with or without process, any person who commits, or attempts or offers to commit, any of the acts or offenses prohibited herein, or who commits any offense against the laws of the United States; but no person shall be arrested without process for any offense not committed in the presence of the marshal or his general or special deputies, or either of them, or of the supervisors of election, or either of them; and for the purposes of arrest or the preservation of the peace the supervisors of election shall, in the absence of the marshal's deputies, or if required to assist such deputies, have the same duties and powers as deputy marshals; nor shall any person, on the day of such election, be arrested without process for any offense committed on the day of registration. SEC. 2023. Whenever any arrest is made under any provision of this title, the person so arrested shall forthwith be brought before a commissioner, judge, or court of the United States for examination of the offenses alleged against him; and such commissioner, judge, or court shall proceed in respect thereto as authorized by law in case of crimes against the United States.