(CNN)For a political party, controlling the White House and Congress isn't the picnic it's made out to be. Politicians who find themselves in this treasured position enter office with grand ambitions, even if they control only slim majorities in Congress. Those ambitions often run into a harsh reality, as the frustrating last few months for the Democrats demonstrate. President Joe Biden has attempted to maneuver a massive domestic agenda through the Democratic Congress, but now heads off to Europe to attend the G20 and COP26 fearing that he might end up with nothing. The political risks are immense. Other Democratic...