Barney Frank

Earlier this week, Rep. Tammy Baldwin said she was "likely" to run for the Senate to become Wisconsin's junior senator. After all of the strife in Wisconsin this spring, it was welcome news to progressives, who lost longtime Senator Russ Feingold in the 2010 midterm election and who have been in agony since Governor Scott Walker took union workers' collective bargaining rights away in support of some of his major donors, who include the Koch brothers. What would a run and win for Ms. Baldwin look like, and what could some of the sticking points be?