I'd point back to at least 2000 and the Supreme Court stopping the count in Florida, but maybe back to when we sabotaged the Iran hostage deal so Carter couldn't have a win
Sure, both are good examples of democracy being attacked. More broadly, I'd point to all the lies the public is fed to "nudge" us in whatever direction the political parties and lobbyists want. Its not much of a democracy if voters are asked to vote based on massive piles of bad information.