At least 20 percent of Minnesota legislators will not be returning to fight the same battles next year -- and voters have yet to weigh in.

On Wednesday, Rep. Sandra Peterson, DFL-New Hope, added her name to the list of retirees.

The four-term legislator, who concentrated much of her efforts on education issues, cited "recent, unexpected health concerns" when she announced her retirement.

"I need to refocus my energies onto [recuperation] and spending time with my family," Peterson said.

So far, 24 Republicans and 17 DFLers have said they won't be back in January, but the tally of voluntary retirements won't be definitive until June 5. That's when candidates must have their paperwork on file with the secretary of state.

No matter what happens in November, the legislative class of 2013 will be losing significant experience.

Many of the giants of the Legislature are moving on. Their names include legislators who have shaped Minnesota's policies for decades. Among them: Senate Finance Chairwoman Claire Robling, R-Jordan; bonding expert Sen. Keith Langseth, DFL-Glyndon; Sen. Gen Olson, of Minnetrista, long a GOP lead on education; Rep. Mindy Greiling, of Roseville, long a DFL lead on education; Minneapolis maven DFL Sen. Linda Higgins and DFL Rep. Tom Rukavina, who has represented part of the Iron Range for a generation.

All declared they simply had had enough of Capitol work. In announcing she would not run for re-election, Robling voiced fear that "statesmen are vanishing as partisanship deepens."

But for all those moving on, some are looking to move up. A handful of House members are running for the state Senate, two legislators looked at U.S. House seats and one -- the recently endorsed Republican state Rep. Kurt Bills -- hopes to join the U.S. Senate.

The rate of turnover is sure to grow. In the past decade, voters opted for new faces in about a third of the House and Senate seats.

Rachel E. Stassen-Berger Twitter: @rachelsb