Tuesday's primary defeat of Indiana's Lugar probably will encourage other Republican candidates to wonder whether they should emulate the no-compromise style of Indiana State Treasurer Richard Mourdock, who trounced the senator.
Lugar was part of an already-vanishing breed: the cool, cerebral legislative craftsman who values bipartisan compromise. Sen. Olympia Snowe (R., Maine) is retiring this year, and she cited the increasingly ugly partisanship in Congress as her motive. Democratic moderate Kent Conrad of North Dakota, the chairman of the Senate Budget Committee, also is retiring, as is Connecticut independent Sen. Joe Lieberman, another cross-the-aisle dealmaker.
Veteran Sen. Orrin G. Hatch (R., Utah), who used to strike compromises with Democrats, spent the last two years showily avoiding such deals after tea party opposition toppled his Utah colleague Robert Bennett, a conservative Republican, in 2010. Hatch easily survived a challenge from the right at his state convention last month, but he still faces a primary June 26.
However, some analysts warned against reading too much into Lugar's defeat, which was rooted in more than ideology. He was widely perceived as out of touch with the folks back home - more comfortable discussing foreign affairs than constituent concerns - and he was hit by an avalanche of negative ads from well-financed advocacy groups.
Lugar's Washington allies were upset. "The alarm bells have been sounded," Sen. John Kerry (D., Mass.) said in a Senate floor speech extolling Lugar.
They've been sounding for years. Since 2009, most big legislation has passed on straight party-line votes. President Obama's three signature congressional achievements - overhauling the nation's health-care system, revamping Wall Street regulation and pumping hundreds of billions of stimulus dollars into the economy - were approved with virtually no Republican support.
Efforts to raise the nation's debt ceiling, usually a routine matter, resulted in an ugly battle last year that led to a drop in the government's credit rating. That's likely to flare again later this year.
Mourdock's 22-point victory, greater than anticipated, energized conservatives, who view it as another successful chapter in their epic struggle for the Republican Party's soul. An array of conservative powerhouses backed Mourdock, including 2008 vice presidential nominee Sarah Palin, no-new-tax guru Grover Norquist, the National Rifle Association and the Indiana Right to Life political arm.
The most worried Republican on Wednesday may have been presumptive presidential nominee Mitt Romney. Never a favorite of conservatives, he's been trying hard to demonstrate that he's one of them. But to win the general election, he's going to have to reach to the middle, too.