Washington (CNN) Pennsylvania's Republican Party is asking for an investigation into Tuesday's special election.

The party has asked the Pennsylvania secretary of state to look into "a number of irregularities" it says occurred during voting in the House race between Republican Rick Saccone and Democrat Conor Lamb.

In a letter, Pennsylvania GOP general counsel Joel Frank said there had been complaints of voting machines not being calibrated, voters not appearing on voter rolls, questions over website information on polling places, and notice of overseas and military voting.

A letter addressed to the US Department of Justice from Frank also requests the appointment of federal observers "to monitor" the May 15 primary "for practices that may infringe on the ability of all duly qualified Pennsylvania voters to cast their votes in accordance with the voting protections afforded under federal laws."