Wiktionary
n. (context US colloquial Politics English) A supposed conspiracy perpetuated by members of the Republican Party.
Wikipedia
"Vast right-wing conspiracy" is a conspiracy theory referenced by then First Lady of the United States Hillary Clinton in 1998 in defense of her husband, President Bill Clinton, characterizing the continued allegations of scandal against her and her husband, including the Lewinsky scandal, as part of a long campaign by Clinton's political enemies. The term has been used since, including in a question posed to Bill Clinton in 2009 to describe verbal attacks on Barack Obama during his early presidency. Hillary Clinton mentioned it again during her 2016 presidential campaign.
Usage examples of "vast right-wing conspiracy".
Now there's even a documentary version of liberals' Vast Right-Wing Conspiracy fantasy The Hunting of the President.
This is - the great story here for anybody willing to find it and write about it and explain it is this vast right-wing conspiracy that has been conspiring against my husband since the day he announced for president.