Former House Speaker Newt Gingrich (R) came to the defense of Delaware GOP Senate nominee Christine O'Donnell, who pulled off a shocking victory over Rep. Mike Castle in a Tuesday-night primary race.

Gingrich, who has said he is exploring a 2012 presidential bid, said that she is an "electable" candidate despite what the "elite media" believes and cautioned there will be an effort to "discredit" her like Nevada GOP Senate nominee Sharron Angle, who faces Majority Leader Harry Reid (D).

"Christine odonnell won in delaware. She got more votes in the primary. The elite media wants to declare her unelectable — nonsense — she won," he posted on his Twitter account. "There will be an all out effort to discredit christine odonnell in delaware just as there was to discredit sharon angle [sic] in nevada."

O'Donnell's win, which was in part spurred by Tea Party groups in heavily Democratic Delaware, caused election handicappers to shift their projections in the state's Senate race. Many who predicted that the heavily favored, centrist Castle could defeat Democratic candidate Chris Coons now say he will beat O'Donnell in a general-election match-up.

Many GOP political professionals have said that O'Donnell's victory will cost their party a Senate seat, including former top George W. Bush adviser Karl Rove.

But during the midterm election cycle, Gingrich has made multiple appeals to Tea Party groups and other activist elements within the Republican Party.