Tea party takes top Senate scalp
Top US senator Richard Lugar has lost a hard-fought primary contest to a challenger backed by the right-wing tea party movement, ending his nearly 40-year career.
In Indiana, the biggest race of the night, Mr Lugar, 80, the highest-ranking Republican on the Senate Foreign Relations Committee, lost to tea party-backed state treasurer Richard Mourdock, who will face Democratic congressman Joe Donnelly in the November general election.
Before the polls had closed, Democrats were promising to compete hard against Mr Mourdock. Republicans need to gain four seats to take control of the US Senate, and a Lugar loss "gives Democrats a pick-up opportunity", said Senator Charles Schumer, a New York Democrat.
Earlier, Mr Lugar made clear he would stand by the primary's outcome, ruling out running as an independent. "This is it," he said.
Playing out in a conservative state, the race illustrated the electorate's animosity towards many incumbents and anyone with deep ties to Washington.
That was clear when Mr Lugar, who has not faced questions about his residency in decades, found himself on the defensive over whether he lived in Indiana or northern Virginia.
He was also cast as too moderate for the conservative Republican Party in Indiana and he was criticised for his work with Democrats on issues such as nuclear non-proliferation, underscoring deep polarisation in the country as well as a split in Republican ranks between the establishment wing and the insurgent conservative tea party movement.
The tea party advocates small government, deep spending cuts and no tax increases, disdaining compromises with Democrats.
On Capitol Hill, Republicans braced for a Lugar loss throughout the day. "It says if you're an incumbent, you better not lose touch with home," said South Carolina Republican senator Lindsey Graham.
The Mourdock vs Donnelly match could develop into a hotly-contested race with the potential to affect the White House contest.