"electoral performance" is a correct and usable phrase in written English.
For example, you could use it in a sentence such as, "The party's dismal electoral performance was a shock to many political analysts."
Labour's electoral performance was mixed.
Well, more support generally results in better electoral performance.
"The Electoral Performance of Center-Left Parties: Putting 'Decline' in Perspective". Progressive Politics After the Crash.
Afterwards, however, the party's underwhelming electoral performance will limit Mr Chávez's freedom to govern.
Overall, the relationship between job growth and electoral performance is good but not great.
Their electoral performance has been wilting ever since Millhead, for the want of a conspicuous success.
Angela Merkel's strong 2013 electoral performance is helpful; export-minded Germany is a staunch TTIP supporter.
And he often suggests that his electoral performance was a victory, given the odds against him.
("Performance" refers to measures of electoral performance, rather than of governance).
Growth rates during an election year are a good but imperfect indicator of electoral performance.
Taking his poor electoral performance to indicate popular distrust, Mazowiecki resigned in January 1991.
