According to leading liberal blog DailyKos, the following Democratic Senators have not yet signed on as sponsors of the Senate version of the Employee Free Choice Act, which Senator Kennedy is expected to introduce at or before the upcoming Senate Health, Labor, and Pensions Committee Hearings: 

• Patrick Leahy  (D - VT)
• Ben Nelson (D-NE)
• Bill Nelson (D-FL)

The site also states that Senator Arlen Specter (R-PA) will be a co-sponsor and lists several other Republicans it believes can or should be persuaded. 

• Wayne Allard (R-CO) [Kos quote:  "He's retiring, so can afford to go against his party!"]
• John Sununu(R-NH) [Kos quote:  "He's our #1 2008 target right now, and scared."]
• George Voinovich(R-OH) [Kos quote:  "received the 2nd-best 2006 rating from SEIU of any Republican"]
• Richard Lugar (R-IN) [Kos quote:  "good SEIU ratings"]
• Chuck Hagel(R-NE) [Kos quote:  "good SEIU ratings"]
• Elizabeth Dole(R-NC)
• Lamar Alexander (R-TN)
• Gordon Smith (R - OR)
• Ted Stevens(R - AK)
• Susan Collins(R - ME)
• Olympia Snowe (R - ME)
• Norm Coleman (R-MN)

That "persuasion" may include threats to treat these Senators the same as 18 House members were treated by the AFL-CIO and others after those Representatives declined to support labor's agenda: "Americans United for Change Unveils List of Top 18 ‘Public Enemies of the Middle Class’ in Congress."

See also: 

• Until An Employee Exercises A Free Choice -- Rhymes with Right
• Unions Pick at Scabs / Democrats Reward Unions -- GM's Corner
• Replacement Worker Finds His Car Torched -- Editor & Publisher
• Do Unions Respect Dissent?
• Labor's Rhetoric Demonstrates that Secret Ballots are Necessary