SIOUX FALLS - Senator Tim Johnson is set to announce Tuesday whether he will seek re-election in 2014.

Questions surrounding whether the three-term Democratic senator would seek re-election have been swirling for months.

Johnson spokesman Perry Plumart tells The Daily Republic that the announcement will come Tuesday. Details of when and where the announcement will take place have not been released.

There is speculation that if the 66-year-old doesn't run, his son, Brendan, might. Brendan Johnson is currently the U.S. Attorney in South Dakota.

Former South Dakota Gov. Mike Rounds has announced he is seeking the Republican nomination for the Senate seat now held by Johnson.

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