By the 2008 presidential election, voters around the country are likely to see sweeping changes in how they cast their ballots and how those ballots are counted. New federal guidelines, along with legislation given a strong chance to pass in Congress next year, will probably combine to make the paperless voting machines obsolete. Motivated in part by voting problems during the midterm elections last month, the changes are a result of a growing skepticism among local and state election officials, federal legislators and the scientific community about the reliability and security of the paperless touch-screen machines used by about 30 percent of American voters. Various forms of vote-counting software used around the country ... will for the first time be inspected by federal authorities, and the code could be made public. Last year, New Mexico spent $14 million to replace its touch screens. Other states are spending millions more to retrofit the machines to add paper trails. Because some printers malfunctioned last month, election commissioners in Cuyahoga County, Ohio, which includes Cleveland, said last week that they were considering scrapping their new $17 million system of touch-screen machines. Under changes approved by the Election Assistance Commission yesterday, voting machine manufacturers would have to make their crucial software code available to federal inspectors. The code is now checked mainly by private testing laboratories paid by the manufacturers.