Fewer than one in five registered voters in Massachusetts are predicted to cast ballots in primary elections.
Secretary of State William Galvin forecasts statewide turnout on Tuesday of 14 to 17 percent, or between 600,000 and 700,000 voters.
But Galvin says applications for absentee ballots point to a higher than usual turnout in the Republican primary.
Four years ago about 1 million votes were cast in the primary, when there was a three-way Democratic race for governor. There are no contested primaries for governor this year, but there are primaries for state treasurer and auditor.
About 2.1 million Massachusetts voters are unenrolled, more than all registered Democrats and Republicans combined.
Unenrolled voters can cast ballots in any primary.