4 big stories to watch this week, from taxes to the Russia investigations to Niger

Senate Majority Leader Mitch McConnell, R-Ky., left, President Trump, center, and House Speaker Paul Ryan, R-Wis., will have their relationships tested by the a legislative push on a tax overhaul this week.
Senate Majority Leader Mitch McConnell, R-Ky., left, President Trump, center, and House Speaker Paul Ryan, R-Wis., will have their relationships tested by the a legislative push on a tax overhaul this week.