Washington — — The U.S. Senate will undergo a distinct rightward shift as a result of Tuesday's election, which ushered in conservative, "tea party"-backed candidates and prompted incumbents from both parties to look warily to the next election.
Republicans picked up at least two seats early in the evening — in Arkansas, where Rep. John Boozman defeated Democratic Sen. Blanche Lincoln, and in Indiana, where moderate Sen. Evan Bayh is retiring. Another pickup was expected in North Dakota.
Tea party candidates Rand Paul in Kentucky and Marco Rubio in Florida won Senate seats in those states, which were previously held by Republicans. Rubio beat both Democratic Rep. Kendrick Meek and Gov. Charlie Crist, the Republican who ran as an independent.
Tough battles were underway late Tuesday for long-held Democratic seats across the country from Wisconsin to Washington state. The GOP needed to pick up 10 seats to wrest majority control of the Senate from Democrats, a level of turnover that experts say was unlikely, even in this cycle of Republican ascendance. The GOP gained eight Senate seats during the Republican upheaval of 1994.
Even though some of the long-shot tea party-backed candidates did not win election Tuesday — Christine O'Donnell, for example, lost to Democrat Chris Coons in Delaware — the rightward jolt in the Senate will be apparent.
As voters registered their frustration, the Democrats' 59-seat majority shrank, likely leaving many Democratic senators nervous about advancing President Obama's agenda as their own reelection battles come into view as early as 2012.
Similarly, moderate Republicans will be less likely to cooperate across party lines for fear of primary challenges from conservatives unwilling to compromise.
In the wake of Tuesday's unfolding power shift, the chamber that has been the scene of so many filibuster battles these past two years likely will see a less ambitious legislative agenda.
Democrats in the Senate may find it necessary to adopt a more defensive posture. If Republicans take over the House, the Senate would be Obama's last line of defense in the newly aligned Congress.
"These guys are going to be moving to the right," said Steven Smith, a political science professor and an expert on Congress at Washington University in St. Louis. "The question is, is that the right strategy for two years from now, four years from now? Or will it push the party too far to the right?"
Some of the toughest Senate contests — including several in the West — may not be decided for days.
The most endangered Democrat, Sen. Harry Reid of Nevada, the majority leader, is running against tea-party-backed Sharron Angle. His defeat would launch a post-election leadership battle in the Senate.
Republicans, however, face their own leadership challenges. Sen. Mitch McConnell of Kentucky, the party leader, must welcome outsider candidates — including some whom his party did not initially support.
Several GOP contenders, including Ken Buck, who is in a tight race in Colorado against Democratic Sen. Michael Bennet, found early backing instead from Sen. Jim DeMint (R-S.C.), the conservative kingmaker. They may be less beholden to the upper chamber's stately traditions.
GOP tensions also broke out in Alaska when Republican Sen. Lisa Murkowski launched a write-in campaign after losing her primary to tea party-backed attorney Joe Miller, creating a three-way race with Democrat Scott McAdams, the mayor of Sitka.
The GOP downplays the friction, pointing to the influx of seasoned elected officials, including Rob Portman, the former budget director during the George W. Bush administration, who won in Ohio; Rep. Roy Blunt, the House Republican who won a Senate seat in Missouri, and Dan Coats, the former senator who won his old job back in Indiana.
Obama's former Senate seat in Illinois remained a closely fought battle between Democratic state Treasurer Alexi Giannoulias and Republican Rep. Mark Kirk.