Senate Minority Leader McConnell also released a statement, thanking DeMint "for his uncompromising service to South Carolina and our country in the United States Senate."
"Jim helped provide a powerful voice for conservative ideals in a town where those principles are too often hidden beneath business as usual," McConnell said.
DeMint's departure means there will now be 34 (up from 33) Senate seats up for grabs in the 2014 midterm elections, with the Democrats defending 20 of those seats and the GOP defending 14 (up from 13).
South Carolina will be a busy place that year, as Palmetto State voters will cast ballots for two Senate seats: Along with the special election, senior Sen. Lindsey Graham will be up for re-election. A gubernatorial race will also take place.