Senate Races: What to Watch, Hour by Hour
6:00 p.m.

In states that span multiple time zones, times are for when the majority of the state closes.
The First Results
Look to Kentucky for early evidence of the strength of the year's protest vote. Rand Paul, a Republican, is considered the favorite in spite of some extreme Libertarian views, with polls predicting a solid victory over Attorney General Jack Conway to take Senator Jim Bunning's seat. Will voters express some last-minute doubts about the revolution? Read it here first. In Indiana, former Senator Dan Coats, a Republican, looks to be the prohibitive favorite to take this Democratic seat, even though Representative Brad Ellsworth, a former sheriff from Evansville, has a National Rifle Association endorsement. Mr. Ellsworth has criticized Mr. Coats for his years as a lobbyist, but Mr. Ellsworth bears the albatross of a vote in support of President Obama’s health care plan. The result here could be viewed as an early indicator of how angry voters are at the president’s agenda.
7:00 p.m.

Likely Republican Wins
Marco Rubio, a favorite of the Tea Party insurgency, is likely to win the chaotic election in Florida handily, especially after Democrats tried and failed to persuade their own candidate, Representative Kendrick B. Meek, to quit in favor of Gov. Charlie Crist, an erstwhile Republican running an independent race. Anything else would be big news, and probably spell an early end to the Republican bid to take over the Senate.
In New Hampshire, Kelly Ayotte, a Republican canonized as a "mama grizzly" by Sarah Palin, has already beaten down the Tea Party revolution in the primary, and should win easily over Representative Paul W. Hodes, a Democrat.
7:30 p.m.

A Critical Test for Democrats
The fight to fill the seat of Robert C. Byrd in West Virginia is a critical race for Democrats in their efforts to hold on to the Senate majority. A loss by Gov. Joe Manchin III to businessman John Raese, the Republican, would keep Republican hopes alive for a takeover while a loss by Mr. Raese would greatly complicate the takeover bid. Mr. Manchin was initially considered a shoo-in after Mr. Byrd's death but the hostile poltical climate for Democrats made the race much tighter than expected as Republicans linked Mr. Manchin to President Obama. The governor fought back, focusing on his opponent’s residence in Florida, and late polls had Mr. Manchin ahead.
In Ohio, Secretary of State Lee Fisher, a Democrat, was supposed to be able to brand his Republican opponent, Rob Portman, as a retread from the Bush administration. But Mr. Portman, a former House member, trade representative and budget director, lapped his opponent in fund-raising and the Democratic line of attack never stuck. Mr. Portman is expected to breeze back to Washington and is already talked about as a 2012 vice-presidential prospect.
8:00 p.m.

The First Real Tossups
The first Senate elections of the evening that are rated as legitimate cliffhangers by the polls will start to come in at 8 p.m. Look to returns from Pennsylvania for evidence that the door-to-door campaigning of organized labor can have some impact in a state where outside groups have spent millions on television advertising. Pat Toomey, a Republican, has a narrow lead, but this race has been neck and neck for months.
Republicans are counting on the Illinois Senate race in their uphill effort to grab the Senate majority and also as a symbolic victory over President Obama in his home state. Representative Mark Steven Kirk, the Republican, has come under fire for misrepresenting his military record while he has attacked Alexi Giannoulias, a Democrat, for a checkered banking record.
In one of the most-discussed Senate races of the year, Republicans will probably view Delaware as a missed opportunity unless Christine O'Donnell can conjure a miracle. Ms. O'Donnell, backed by the Tea Party movement, has consistently trailed Chris Coons, the Democratic executive of New Castle County, since upsetting Representative Michael N. Castle in the primary. A win by Ms. O'Donnell would be a surprise and would mean that Republicans are having a sensational election night.
Look to the race in Connecticut as a bellwether of what money can and can't buy. Linda McMahon, a wrestling impresario, has spent $42 million of her own money, but still trails Attorney General Richard Blumenthal, a Democrat. Will Ms. McMahon's recent switch to gentler advertising make a difference to women voters, who have viewed her with suspicion?
In Missouri, Representative Roy Blunt, a Republican, has been stretching his lead in the polls over Secretary of State Robin Carnahan since summer, and there may be little suspense in this race.
8:30 p.m.

Arkansas
The prospects of Representative John Boozman, a Republican, continue to look rosy, as they have consistently throughout the election season. It will be big news if the Democratic incumbent, Blanche Lincoln, makes up the 20-point gap polls have shown in the last few weeks.
9:00 p.m.

The Showdown in Colorado
The ultracompetive and expensive Colorado race is one of the most important of the night. A win by Michael Bennet, the Democrat appointed to the Senate last year, over Ken Buck, a Republican, would give Democrats a little breathing room in their efforts to hold the Senate as the election moves to the West Coast. Mr. Buck, a federal and state prosecutor, has strong Tea Party backing, but Mr. Bennet has used the Republican's conservative social stances against him, winning over women Mr. Buck has had narrow leads in polls. A Republican loss would be viewed as another race where the Tea Party movement cost establishment Republicans a seat.
In Wisconsin, Russ Feingold, the three-term maverick Democrat, has survived tough elections in the past but might not pull off a comeback this time. Ron Johnson, a Republican businessman, has capitalized on a surly mood among Wisconsin voters to put Mr. Feingold on the defensive over his support of the health care law and other administration initiatives. Mr. Feingold, an author of the campaign finance law, has also been the target of heavy spending by the kind of outside groups he has opposed. Republicans expect to win this seat.
A close race in Louisiana would be surprising. The incumbent Republican, David Vitter, is well ahead in polls, and has seemed to survive the reminders from his opponent, Charlie Melancon, that Mr. Vitter was caught up in a prostitution scandal in 2007.
10:00 p.m.

Tossup in Nevada
Last-minute deciders hold the key to the race in Nevada, where the Democrats’ Senate leader, Harry Reid, is on the line. A Tea Party favorite, Sharron Angle, is fueled by phenomenal fund-raising in the third quarter, and a boost from independent groups backed by anonymous donors. The race is a statistical dead heat in the polls. Mr. Reid had plenty of resources of his own for last-minute campaigning. But unless the anti-Democrat wave has crested, he will be out of a job.
11:00 p.m.

The West Coast Weighs In
Washington has become a battlefield, with independent groups pouring $20 million into advertising in the last few months. Patty Murray, the incumbent Democrat, and Dino Rossi, a Republican, are in one of the closest races in this election. If Ms. Murray pulls it out, it could be because her critique of the anonymous wealthy donors financing the campaign against her gained traction. If not, count the libertarian Mr. Rossi as a beneficiary of the anti-deficit, anti-Obama surge. In California, outside groups have spent nearly $9 million trying to oust Barbara Boxer, but polls have suggested California could be the Democrats' bulwark against a Republican takeover. If Carly Fiorina wins here, she will have overcome a fairly consistent five-point disadvantage in the last hours of the campaign.
12:00 a.m.

The Last Races
The last election of the night could be one of the most compelling, but don’t be surprised if the result is not known for weeks. A statewide spelling bee will test Alaskans' ability to correctly write in the name of their incumbent senator, Lisa Murkowski. She lost the Republican primary to Joe Miller, who has Sarah Palin's support, but refused to drop out. Counting her write-ins could take a long time. What might be clear earlier, though, are the prospects for the long shot of the evening, Scott McAdams, the Democratic mayor of Sitka who could win if Republicans split their votes.