Smooth Sailing

The opposite of rough sailing, smooth sailing implies particularly easy progress with little effort required.

Smooth sailing would be sailing in calm waters.

Example: In a normal election year, incumbent politicians (those who are running for re-election) usually have smooth sailing when running against their challengers. Incumbents generally raise much more money than those who would challenge them; failing this, they have established political connections, name recognition, and existing public support. The 2010 mid-term elections appear to be an exception to this general rule; incumbents are endangered by widespread dissatisfaction with the government and its management of the stagnant U.S. economy.