MADISON, Wis. -

The turnout for Wisconsin's Aug. 14 primary could come close to matching a 20-year high in balloting that doesn't include voting for governor. So says the state's Government Accountability Board.

The panel on Tuesday predicted that 20 percent of Wisconsin's voting-age population will turn out for the primary that includes a four-way Republican race for the U.S. Senate.

The report was released Tuesday, three weeks before the election. That equates to about 870,500 voters. The highest turnout in a non-gubernatorial fall primary in the past 20 years was 21 percent in 1992.

This is the first year that Wisconsin's fall primary comes in August. It used to be a month later in September.

In addition to the U.S. Senate race, there are also primaries in two of eight congressional districts, five of 16 state Senate districts and 39 of 99 Assembly districts.