The surest indication of whether a bill will be pushed through Congress right now is not a speech from President Obama or a declaration by House Speaker Nancy Pelosi (D-Calif.). Instead, it's often a letter from the office of a Massachusetts senator who has served in Washington for less than seven months. When Sen. Scott Brown (R) announced in a written statement Monday he would back a briefly stalled bill to reform the financial regulatory system, two other Republicans quickly joined him. The three helped prevent a Republican filibuster of the legislation on Thursday morning, clearing the way for a...