In Kirk's case, vote fraud.
Every single viable conservative who was "considering" filing in the primary against Kirk was bullied behind the scenes by the establishment and told to endorse Kirk OR ELSE (State Rep. Jim Durkin, the 2002 GOP nominee against Durbin, for example, threatened to run against Kirk, then immediately backtracked and endorsed him in the primary the next week)
A tainted and corrupt Chicago machine Democrat with dismal approval ratings was put up as the "fall guy" against Kirk, so either way the machine would get a liberal in the Senate. Kirk was such a pathetic RINO candidate that he STILL ran a horribly flawed campaign (got caught lying about his military record, which the mainstream media ignored but was eventually forced to report on when Kirk made up ridiculous B.S. like he had "commanded the pentagon war room")
EVERY single poll, conducts for weeks leading up to election day, showed "electable" Mark Kirk was trailing in the race, and behind the "unelectable" conservative nominee for Governor, with EVERY demographic group in Illinois (seniors, college students, hispanics, suburban voters, downstaters, etc.)... then, low and behold, on election day... Kirk somehow "wins" and the conservative "loses".
Kirk does "better" than the conservative in places where he had zero ground game and didn't even lift a finger to campaign, which "proves" liberal Republicans are more "electable"
Mark Kirk eagerly posed for photo ops with Obama after supposedly being elected to "embarrass" and "stop" him, and he and his liberal Democrat "opponent" went out to lunch together the following week, got all kissy with each and even exchanged "gifts" while slapping each other on the back:
The really pathetic part is some conservatives have actually drank the kool-aid that this "proves" that "only moderates are electable"