DES MOINES — Former Iowa House Speaker Pat Murphy has filed his nomination petitions foe the U.S. House 1st District race.Murphy, a former Dubuque legislator, received verification from the Iowa Secretary of State that his nominating petitions have been accepted.“From the beginning this has been a grass roots campaign, and I’m proud to have the signatures of Democrats from across the 1st District making this filing possible,” said Murphy.To be placed on the ballot, candidates are required to collect signatures from eligible voters totaling 1 percent of votes received for the top of the ticket in the previous year’s election, and 2 percent from at least 10 counties in the district.