Richard Lugar, longtime senator from Indiana, was defeated in the Republican primary by Richard Mourdock,  supported by Tea Party elements.

Roy Beck of Numbers USA had a good analysis of the Lugar defeat:

No matter which Party wins in November, the Indiana Senate seat now held by Richard Lugar should produce far better immigration actions in the future.  Democrat primary winner Joe Donnelly has a B+ Career immigration grade in the U.S. House. And the GOP primary victor, Richard Mourdock, filled out the NumbersUSA survey to earn the title of TRUE REFORMER, supporting all 12 of our immigration stances. In addition, the Libertarian primary victor, Andrew Horning, filled out our survey and looks almost as good as Donnelly on immigration...

Finally, the workers of Indiana — and the country — will have a U.S. Senator from Indiana who cares about their interests when it comes to immigration...

Like many Senators who serve for many terms, Sen. Lugar was vulnerable to charges that he no longer had a good feel for the needs of his state's voters. ..Indiana Secretary of State Mourdock challenged Lugar in part because of his constant leadership in pushing for amnesties for illegal aliens who have illegally stolen U.S. jobs....Sen. Lugar never met an amnesty he didn't like, voting for amnesties 15 times. ..We rated Sen. Lugar on 85 immigration actions since 1989.  When each action was weighted according to the numerical impact, we found that he acted 81% of the time in favor of foreign workers and dependents over the interests of U.S. workers and dependents.That earned him a D-minus over his career, making him the worst Republican in the Senate (Sen. John McCain of Arizona is runner-up)...

Defeated-Sen. Lugar is worst immigration Republican in Senate —both GOP & Dem Indiana primary victors MUCH better  Roy Beck, Numbers USA, May 8th, 2012