Former Massachusetts Gov. Mitt Romney (R) will travel to South Dakota Friday to campaign for Sen. John Thune (R-S.D.)

The event joins two possible 2012 presidential candidates. Most believe that Romney, who ran for president in 2008 will run again in 2012 and some see Thune making a White House bid at the end of President Barack Obama's first term.


Thune announced the event in a Facebook note Thursday.

The announcement comes on the same day Romney addressed right-wing activists at the Conservative Political Action Conference (CPAC) in Washington.

"Remember he gave himself that B-plus for his first year in office? Tell that to the 4 million Americans who lost their jobs last year,” the former Massachusetts governor told the CPAC crowd. "President Obama's self-proclaimed B-plus will go down in history as the biggest exaggeration since Al Gore's invention of the internet."

The first-term South Dakota senator is considered a rising star in the GOP and some have said that he may enter the 2012 presidential race as well. 

Both Thune and Romney appear on the CPAC straw poll this year. Romney has won the past three straw polls.

Thune is expected to win reelection to the Senate.