Earlier today I mentioned that the Senate club was working to protect Blanche Lincoln, first by allowing her to offer up a kabuki derivatives bill which was strong enough for her to counteract claims of being too tight with Wall Street, then by delaying the eventual watering down of that piece in the overall bill until after her Senate primary. I’ve heard that Lincoln couldn’t even defend the concept of forcing the big banks to spin off their swaps trading desks in a caucus luncheon; Maria Cantwell had to do it for her. Clearly, she was fed the most left-leaning derivatives package available, with the expressed intention that it wouldn’t make the bill. Nobody wants to overturn it before it serves its purpose of getting Lincoln nominated for re-election, however.

That could be complicated by the possibility of a runoff that would extend the Arkansas primary out to June 8.

Less than a week before their Senate primary, Sen. Blanche Lincoln and Lt. Gov. Bill Halter are preparing for their acrimonious contest to head into overtime.

With recent polls showing Lincoln with less than the 50 percent of the vote needed to avoid a runoff as a relatively unknown conservative candidate has gained his support at her expense, Arkansas observers say a second election on June 8 between the two top finishers is increasingly likely.

“Certainly, a runoff election remains a distinct possibility,” acknowledged Lincoln campaign manager Steve Patterson in a memo. “The fact that Senator Lincoln has withstood two months of negative attacks from well-funded outside groups and still remains in a strong position is a testament to her toughness and popularity among Arkansas voters,” he added.

This would screw things up considerably. The Democratic leadership and the White House have said repeatedly that they want a Wall Street reform bill finished by Memorial Day. Waiting until June 8 pushes back a lot of the other things they want to get accomplished in this Congressional session. Furthermore, the delay would be needless, and a clear attempt to protect Blanche Lincoln, which Republicans would jump all over. It wouldn’t be tenable after some point.

Given this, Democrats have two options – give up the charade and change the derivatives piece before June 8, with Lincoln having to suffer the consequences; or leave it intact to do its intended purpose, and actually pass a substantive and wide-ranging change to how Wall Street does its business. I’ll bet lots of people in the Democratic leadership and inside the White House are hoping that Lincoln gets over 50% next Tuesday so they don’t have to make such a determination.

UPDATE: Daily Kos’ latest poll shows the likelihood of a runoff in this race. That’s really good news, in a substantive sense. Halter still runs better in trial heats against Republican opponents than Lincoln.

Meanwhile, SEIU’s new President Mary Kay Henry just warned that they’ll sit out the general election if Lincoln defeats Halter.