Forcing Republican union members to support Democrat campaigns

Rasmussen Reports has a new poll that shows significant percentages of union members' dues are going to support political parties that they don't agree with.

A Rasmussen Reports telephone survey finds that 50% of public sector union members are ready to vote for a Democratic congressional candidate from their district, while just 22% would vote for a Republican. Ten percent (10%) would prefer a third party option, and 18% are not sure at this time.
Among private sector union members, 47% would vote for a Democrat and 34% for a Republican. Seven percent (7%) would prefer a third party candidate, and 11% are undecided. . . .

Here is a different way of looking at it. Unions obviously give money to support liberal causes.

Union members are more politically liberal than the population at large. Among all union members, 32% are conservative, 34% moderate and 32% liberal. Among all voters nationwide, there are twice as many conservatives as liberals. Even in this area, there is a modest gap between public and private sector union members.
Thirty-six percent (36%) of public sector union members are politically liberal, while just 27% are conservative.
For private sector unions, the numbers tilt in a slightly different direction—35% conservative and 30% liberal. . . .