Answer: it has a strong effect. The president and the Congress experience a kind of honeymoon if the popularity of the president is high after the election. The so called "honeymoon" period can be very productive.
Explanation: When a president's popularity tends to be highest right after an election. The president's love affair with the people and with Congress can be consummated. Franklin Delano Roosvelt enjoyed a honeymoon in his first 100 days. From March to June 1933, FDR obtained from a willing Congress a vast array of new laws creating new agencies and authorizing new powers. But that was also because America was in one of the worst depressions ever.
