To attack a political opponent in a particularly vicious, partisan manner. Also: bork.
With similar regret, other Capitol Hill veterans insist there truly were better times of partisan disputation focused on ideas—before “to Bork” was coined as a political attack verb, from the undermining of a Republican Supreme Court nominee.
—Francis X. Clines, “Partisan Rancor: Not Always So Bad for the National Soul,” The New York Times, March 12, 1997
In Washington, a favorite game is to “bork” an enemy, as in, “We borked that right-wing nut.” Conservatives have been plotting their revenge ever since triumphant Democrats made Supreme Court nominee Robert Bork’s name a verb in 1987. To right-wingers, the silver lining in George Bush’s defeat is the chance to bork one of Bill Clinton’s liberal nominees — payback for the way Senate Democrats treated Bork, John Tower and Clarence Thomas.
—Bob Cohn “Crowning a ‘Quota Queen’?,” Newsweek, May 24, 1993
The senator best throw down his axe as he is “Borking” up the wrong tree. Unless he does, he will get lost in the forest of obscure politicians and will end up just “Biden” his time.
—“Democrats ‘Borking’ Up the Wrong Tree,” The Belleville Telescope (Belleville, Kansas), September 17, 1987
Here's an even earlier cite that uses this verb in a slightly different way:
“Stone’s Dictionary of Eponymous Neologisms” lists the following:...
Bork vt. — to set back (Reagan’s Supreme Court appointment Borks blacks and women).
Unhappily, on the Constitution’s 200th anniversary, that document has been Borked by Reagan’s appointment.
—Chuck Stone, “Borking the Constitution,” The Index-Journal (Greenwood, South Carolina), August 11, 1987