In an era that increasingly relies on paperless technology, Maryland is about to revert to using old-fashioned pen and paper to elect its leaders. The Board of Public Works is expected to approve a $28 million contract Wednesday to replace Maryland’s touch-screen voting system with machines that scan paper ballots, which voters will mark with a pen or pencil. The contract comes more than seven years after the legislature decided the state should replace tens of thousands of touch screens deemed unreliable and susceptible to fraud. Since then, arguments and tough budget times have repeatedly delayed efforts to replace the machines with a system that has a verifiable paper record. “We, for a generation of elections, have had no paper trail,” said Del. Jon Cardin, a Baltimore County Democrat and a leading proponent of scrapping the touch-screen system. The new system is expected to be in place for the 2016 presidential election.