The new system would cost $18 million to $20 million and would mark the second time in five years that the state has overhauled its voter system.
"What's happened is ground-breaking," said John Schneider of the Maryland Election Integrity Coalition, one of the groups backing the legislation. "After an effort going on three or four years, things finally came together in a rush."
A similar bill was passed by the state's House of Delegates but many delegates were surprised the Senate approved the measure as well.
"I had written [the bill] off," said Del. Sheila E. Hixson, chairwoman of the House Ways & Means Committee. "The good news is that this bill won't take effect until 2010, so we have time" to work out differences.
She said she likely would recommend that the House approve the Senate-based measure, avoiding a conference committee, and that differences be worked out next year when funding is considered.
Gov. Martin O'Malley has not taken a position on the bill.
If O'Malley does sign, most counties would rely on optical-scan machines, which are already used to tally absentee ballots.
Both versions of the paper-trail legislation would require audits of the new system. The Senate version would allow state election officials to determine how those audits would be conducted, while the House version spells out the procedures in detail.
The two bills also differ in how they ensure that visually impaired and other disabled voter have the ability to case ballots without assistance. House lawmakers crafted precise language with the assistance of members of the disabled community; the Senate version is more general.