Longtime state Sen. Pat Pariseau, a Republican from Farmington, and state Sen. Jim Vickerman, a Democrat from Tracy, both announced they would not run for re-election Monday.

Pariseau won her last election with 57 percent of the vote but two Republican challengers have filed for the seat this year. They are Bob Erickson of Lakeville and Theresa Stokes of Farmington. Update: Dave Thompson, a Republican who ran for state party chair 2009, came by the Capitol office to say that he has filed for the seat as well.

"I have been carefully considering my retirement for quite a while now and want to step aside to let a new voice represent my beloved Senate district in St. Paul," she said in a statement. Pariseau has been in the Legislature since 1988 and was well known for her outdoors and pro-gun issues.

Vickerman, who has been in the Legislature for 24 years, did not have a Democratic challenger. He won his last election with 58 percent of the vote but Republican presidential candidate John McCain and Republican Senate candidate Norm Coleman both won his district in 2008.

"I couldn't be more proud to have been a voice for farmers and veterans at the Capitol," he said in a statement.

At least three other longtime Senators have announced retirement:

Sen. Dick Day, R-Owatonna, stepped down from his seat mid-term to lobby. His replacement was picked in a January special election.

Sen. Steve Murphy, DFL-Red Wing, announced before the start of this year's session that he would not run again.

Sen. Steve Dille, R-Dassel, announced in November that he wouldn't seek re-election because he would have had to battle his party for endorsement.

Pariseau and Dille are among of a handful of state Senators potentially facing interparty fights. Here are some of the others with recently filed challengers running against them:

Sen. Paul Koering, R-Fort Ripley, has a Republican challenger in Paul Gazelka, who lost his House seat in 2006. Koering won a contested endorsement fight four years ago and survived a primary.

Sen. Gen Olsen, R-Minnetrista, may go up against David Osmek, at the Senate District 33 convention next month. (see update)

Sen. Debbie Johnson, R-Blaine, lost her party's endorsement last weekend to Michelle Benson. (Update: In regard to questions about her electoral future Johnson said: "I will make up my mind after session is over…I'm leaving all my option open." Asked if running in a primary is one of those options, she said: "I'm not even going to address that.")

Sen. Linda Higgins, DFL-Minneapolis, drew a challenge from Raymond Dehn, who filed for the seat last year.

Sen. Dick Cohen, DFL-St. Paul, has an opponent in Don Arnosti, who filed for the seat last February.

Update:

Sen. Gen Olson, R-Minnetrista, said that she plans to run for re-election in 2010 but will not run again in 2012 (after redistricting.) She said David Osmek told her that he filed a committee to gear up to run in 2012 but will not run in 2010.

"He's not running against me," Olson said.