Hi
Tinanam;
It
Anonymous“
"The president rode into office on a tide of discontent"
”
This is a wonderful metaphor, as aonther poster beautifully explained concerning the physical tides of the oceans and seas on earth.
Have you seen surfers on surfboards on the coast of California or Hawaii where the waves are very big? They "ride the waves on to the shore".
The "shore" in your sentence is the office of president, and the tide is the sentiment of the voters, who figuratively carried him into the office by the force of their votes in the election. The force of the votes is the energy of the tides, driven by the voter's sentiment of ill-feelings toward the existing political situation.