Washington ? The already-cantankerous debate over high-tech voting machines, which have been installed in great numbers in recent years, is growing more intense and convoluted as primaries get underway and the midterm election nears.

A coalition of voting rights activists and prominent computer scientists argues that some of the machines are not sufficiently secure against tampering and could result in disputed elections, while voting machine vendors and many election officials say that view is exaggerated.

The latest dispute occurred several weeks ago after it was discovered at a test in Utah that someone with a reasonable knowledge of computer code could gain access to and tamper with the system software on a popular brand of voting machine manufactured by Diebold Election Systems.

The developments prompted California and Pennsylvania to send urgent warnings to counties that use Diebold’s touch-screen voting systems to take additional steps to secure them.