Joe Biden's theory of the case is that his current support among black voters will lead to success in Nevada and South Carolina. That, in turn, he hopes will propel him to victory in the Super Tuesday contests in early March.Michael Bloomberg, along with other candidates, hope to earn the support of black voters and…

President Trump's decision to kill a top Iranian general has split the Democratic field along familiar ideological lines. It remains to be seen how much the issue will ultimately matter to primary voters, something that will depend in part on whether the conflict between the United States and Iran continues to escalate.This episode: congressional correspondent…