"It is apparent that both Congressman Berg and I have very passionate, committed supporters in the Republican Party," Kalk said in a statement. "That passionate support, on both sides, is a vivid example of the strength of our party as we move to 2012. It does, however, create a possible and dangerous split coming out of the convention. While I remain convinced that we would have emerged with the endorsement, I am not willing to risk a divided party heading into the general election."
The seat came open when Sen. Kent Conrad (D) announced his retirement this year. It is the Democrats' most vulnerable seat, as the party has no real bench of candidates in the state.