MIAMI, May 3 — Florida legislators voted on Thursday to replace touch-screen voting machines installed in 15 counties after the troubled 2000 presidential election here with a system of optical scan voting

The new system is scheduled to be running in time for the 2008 presidential election

The move is the nation’s biggest repudiation of touch-screen voting, which was embraced after the 2000 recount as a way to restore confidence that every vote would count. But the reliability of touch-screen machines has increasingly come under scrutiny, as has the difficulty of doing recounts without a paper trail

With optical scanning, voters mark paper ballots that are counted by scanning machines, leaving a paper trail that remains available for recounts

The 15 counties that will move to the optical scanning, which is in place in the state’s other 52 counties, account for about 51 percent of the state’s 10.4 million registered voters