Reporting from Washington — In a shift of political fortunes that seemed unimaginable even recently, Republicans now have a long-shot chance to take control of the Senate, bolstering their ranks with outsider candidates who would probably shake up the chamber.
Energized conservative "tea party" voters and a sour national mood have proved lethal to incumbents and once-safe Democrats. So, in addition to taking control of the House, which a growing number of national experts expect, Republicans also could gain in the November election the 10 seats needed for a narrow majority in the Senate.
Even if Republicans fall short of winning the Senate, the political wave seems likely to deliver several conservative outsiders whose hot-button proposals and campaign talk about phasing out Social Security probably would present an operational challenge for Senate leaders in both parties.
The expected result is a more polarized Senate — if that's possible in an era when the filibuster, once relegated to civics classes, has become common.
Sen. Tom Coburn, the conservative Republican from Oklahoma, views some of the outsiders "as people who will provide reinforcement," his spokesman said. Coburn and Sen. Jim DeMint of South Carolina are among a handful of Republicans who regularly stage sometimes lonely floor battles to stop what they perceive as excessive government spending.
"The way business has been done in the Senate needs to be threatened and changed," said Coburn spokesman John Hart.
Conservative Senate candidates, such as Sharron Angle in Nevada or Rand Paul in Kentucky, could bolster such efforts. Both have said unemployed Americans should consider accepting lower-paying, entry-level jobs to get back to work.
Another Republican candidate, Pat Toomey in Pennsylvania, is seen as one of the newcomers who could hit the ground running with an understanding of congressional procedure after his three terms in the House and his experience as a past president of the conservative Club for Growth.
Democrats, with 57 senators, joined by two independents, now have an almost filibuster-proof majority. Their numbers swelled during Democratic waves of 2006 and 2008 as voters soured on then- President George W. Bush, the Iraq war and Washington corruption.
Most Republican incumbents are expected to be reelected. Republican candidates also are considered likely to win open seats that had been held by Democrats in North Dakota and Indiana, and possibly others.
Democratic incumbents, meanwhile, are at risk in Arkansas, Colorado, California, Nevada and Washington state.
As a result, Republicans could see a net gain of five to nine seats, analysts say.
States where Senate seats were not even in play a few months ago are suddenly competitive. In Wisconsin, DeMint-backed businessman Ron Johnson jumped into the race in May and has since raised more money than Democratic Sen. Russell D. Feingold in the most recent reporting period.
Electoral waves like the ones in 1980, 1994 and 2006 typically bring candidates who otherwise would have had lesser chances for success.
"When you get a wave, you get a lot of driftwood onto the beach," said Stuart Rothenberg, editor of the Rothenberg Political Report.
Rothenberg and the Cook Political Report said the chance of Republicans taking control is plausible, but it remains a tough climb.
The election of outsider candidates could force the already conservative Republican tent to stretch, posing new obstacles to party unity.
The newcomers are likely to bring the sense of urgency that comes from voter unrest — much the way many of the Democratic senators who arrived after 2006 and 2008 have resisted some of the traditions of the chamber.
Republicans insist the potential ascent of half a dozen conservative outsiders — including Sarah Palin-backed Joe Miller in Alaska and Mike Lee in Utah, who are favored to win after defeating incumbent Republicans in primary challenges — will be balanced by more mainstream candidates.
They point to former Bush administration official Rob Portman in Ohio, seven-term Rep. Roy Blunt in Missouri or former Sen. Dan Coats in Indiana.
Republicans also stress that their party goals are similar to those of the tea party candidates and complain that Democrats are unfairly portraying their candidates as radical.
Nevertheless, the Senate Republican leader, Sen. Mitch McConnell of Kentucky, has yet to outline whether his party would pursue policies being aired on the campaign trail, such as changing Social Security to allow younger generations to contribute to personal savings accounts, as President Bush proposed without success in 2004.
Much of the action in the Senate would depend on Obama's strategy and whether — if his party lost control of one or both chambers of Congress — the president moderates his proposals to win Republican backing, as then- President Clinton did to pass welfare reform.
If Democrats remained in control of the Senate, but with a slimmer majority, it seems doubtful they would have much success peeling off enough Republican votes to reach the filibuster-proof 60-vote threshold typically required to advance legislation.
Even more mainstream Republicans would probably face continued pressure to tack to the political right, lest they become casualties of primary challenges similar to those that toppled fellow Republican senators this year in Utah and Alaska.
"Whatever happens in January, the Senate is still going to be a tough neighborhood," said John Pitney, a politics professor at Claremont McKenna College. "We're either going to have Republican filibusters or Democratic filibusters. It's still going to be a highly polarized body."