PresidentObama, with Speaker Nancy Pelosi (Calif.), greets House Democrats at their retreat. He praised those who were willing to "make tough choices sometimes when they're unpopular." (Melina Mara/the Washington Post) By Perry Bacon Jr. With ...http://www.washingtonpost.com/wp-dyn/content/story/2010/01/14/ST2010011404760.htBy Pablo Martinez Monsivais, AP By Kathy Kiely, USA TODAY WASHINGTON — The Senate is on track for a major makeover as retirements and election defeats change the fa...