How the narrow Senate majority will shape Biden's presidency

In a matter of hours, President Joe Biden will inherit a Democratic-controlled House of Representatives and Senate. But the narrow majorities in both chambers will challenge his administration's agenda, his timeline and the goal Biden set to restore unity in the country after four years of tumult under President Donald Trump.

Bottom line: When Biden is sworn in Wednesday, we still may not know some of the basic tenets of how the Capitol will function during his first two years. There still is not an organizing resolution laying out the rules that will govern the 50-50 Senate over the next two years. We still have no official word on when there will be an impeachment trial, and the fight over fast-tracking Biden's nominees has already begun. Big picture: A normal pace isn't coming anytime soon. Sources have repeatedly told CNN that the next days and weeks will test both parties and the institutions they inhabit. Fights over the constitutionality of impeaching an ex-President are already beginning. Slow-walking Biden's nominees is already underway. And besides the daily business of governing, each party is reckoning with its future. Republicans must recalibrate and decide what their party stands for in the wake of Trump. Democrats -- now finally in power -- must decide how hard they want to push the agenda of their base all the while being governed by a President who has always valued compromise.