Challenges to sitting PMs are not unknown in the unforgiving world of Australian politics.
All that said, Mr. Obama must be aware that not all primary challenges to sitting presidents are about winning.
Lipinski has retained the support of House Speaker Nancy Pelosi (D-Calif ., who has a blanket policy of opposing primary challenges to sitting members.
Today's election also includes several heated legislative contests, including primaries for open seats in Manhattan, Brooklyn and Queens, and primary challenges to sitting legislators in Queens, Manhattan, the Bronx and Westchester County.
There have been very few serious primary challenges to sitting presidents in American history and none have been successful since the advent of the modern primary system.
The challenges relate to sitting, and standing alone, as well as toileting, eating, and dressing.
But they could be pipped by the DUP's Nigel Dodds who is mounting a strong challenge to the sitting UUP MP Cecil Walker.
The New York Times' unraveling of the holdings of the Chinese premier, Wen Jiabao, and his family may be its most direct challenge to a sitting government since its publication of the Pentagon Papers in 1971.
The 28-year-old Colorado Republican, fresh from an unsuccessful but high-profile primary challenge to a sitting congressman, did two things next.
Senator Mike Lee (Utah): Right now probably best known as the guy still willing to sit next to Ted Cruz in the Senate cafeteria, Lee was one of the first candidates to stage a "Tea Party" challenge to a sitting Republican senator.
