Election subversion
Election subversion typically refers to meddling with the vote counting process (whereas voter suppression seeks to disrupt the vote casting process for those likely to vote for a particular candidate). Electoral fraud is a form of illegal election subversion, whereas this article focuses on loopholes in election law to subvert elections. Avenues for election subversion

Disqualification of votes 
Rules that make voting more difficult for some, for example, can become a pretext for disqualifying votes, regardless of whether or not it justifies such a radical action. The independent state legislature theory in the U.S., for example, would allow state legislatures to unilaterally disqualify votes and send their own electors regardless of the vote outcome. Election insecurity 
The lack of election security and other best-practices creates opportunities for compromised election systems/ballots by third-parties. Intimidation and/or replacement of election officials 
By major candidates calling into question the integrity of elections, the ensuing threats towards election officials have led to hundreds of resignations in the U.S. for example, leading to concerns of understaffing and some vacancies being filled by hyper-partisans interested in election subversion. Question/deny legitimacy of election 

This tactic to deny unfavorable results weakens the power of the winners through decreasing the number of citizens who find them legitimate, potentially leading to a breakdown in the rule of law as was seen on January 6, 2021 in the United States. These claims can also be used to try to justify the manipulation of election results in the courts or other bodies of power such as legislatures. Vote buying 
This happens when someone offers money in return for a voter voting a certain way. See also 

 Authoritarianism
 Democratic backsliding
 Electoral fraud
 Fascism
 Unfair election
 Voter suppression

References

Political corruption
Voter suppression
Electoral fraud
Injustice
Political campaign techniques