No matter which party wins control, the new Senate is likely to be less supportive of President Bush on Iraq than the present one, and remain relatively conservative on economic and social issues.
In battleground races, Democrats are sounding a lot like traditional Republicans, emphasizing family values, budget restraint and foreign policy. Some Republicans are sounding more like Democrats as they play down their past support for the Iraq war and distance themselves from an unpopular president.
It's made for some unusual midterm political dynamics.
The current crop of Democratic challengers, particularly in closely contested races, bears little resemblance to yesterday's Great Society liberals.
For instance:
-In Tennessee, Rep. Harold Ford Jr., vying against former Chattanooga Mayor Bob Corker, is defiantly conservative on tax cuts and opposition to gay marriage. He lists the Ten Commandments on the back of his business cards. The two are locked in a close race.
-In Pennsylvania, Democratic challenger Bob Casey, son of a popular former governor, is Catholic and opposed to abortion, as is the Republican incumbent he is trying to unseat, Sen. Rick Santorum. Casey leads in the polls.
-In Montana, Democratic challenger Jon Tester is a farmer who presents himself as the ultimate regular guy, saying he will help average Montanans with tax breaks, including raising the exemption on the estate tax to $5 million. Incumbent Sen. Conrad Burns, burdened by alleged ties to convicted lobbyist Jack Abramoff, is in a close race with Tester.
-In Virginia, incumbent Republican Sen. George Allen is being challenged by James Webb, a former Republican who served as Navy secretary in the Reagan administration. Webb has emphasized his national-security credentials and cultivated a down-home image, emphasizing his rural Virginia background. The two are in a tight race.
-In Missouri, Republican incumbent Jim Talent faces a strong challenge from Democrat Claire McCaskill, the state auditor, who was heavily recruited by Democrats. She has made a greater effort to reach out to rural Missouri, traveling the state in her RV. The race is a statistical dead heat in most polls.
Control of Congress
Democrats need a gain of six seats to reclaim control of the 100-member Senate.
And, although polls suggest their chances of winning the Senate are not as good as winning control of the House, Democrats are widely expected to pick up some seats - if not enough to wrest control from Republicans, then inching closer to the 50-50 Senate that existed for a while early in Bush's first term.
Democrats expect to beat Republican incumbents in Ohio and Pennsylvania, and possibly Rhode Island. The big battlegrounds now are Missouri, Tennessee and Virginia, all held by Republicans.
Also still in play are New Jersey, where Democratic incumbent Sen. Bob Menendez holds a modest lead in polls; and Montana, where Democrats hope to gain a GOP seat but where Republicans were claiming the gap was narrowing in favor of incumbent Burns.
"We've been through this before," Bush said in Billings, Mont., on Wednesday as he campaigned for Burns at the beginning of a save-the-majority tour.
Referendum on change
"We will win the Senate and we will win the House," he declared.
Sen. Chuck Schumer of New York, chairman of the Democratic Senate campaign effort, said he was optimistic about adding Montana and other states with GOP Senate incumbents to the Democratic column.
Schumer claimed unexpectedly strong support for a Democratic challenger in early voting in a race in Arizona, and said it was "harbinger of a wave" that would benefit his party
"The election is becoming more and more a referendum on change," Schumer said.
He said Democrats learned from mistakes they made in 2002 and 2004, and had done a better job this time in recruiting challengers, helping to protect Democratic incumbents, and in fundraising and get-out-the-vote efforts.
With just days to go to the election, Schumer said "there are still intangibles out there" and he didn't want to "give anything a jinx" by predicting that Democrats would regain a Senate majority. Still, he said, "the wind is at our back, the trend seems to be moving in our direction."
Talking the talk, walking the walk
Republicans suggest Democratic challengers may talk like conservatives but won't act like them if elected.
"I think there's a difference between talking a good game and actually being with people on issues that are important to them," said Dan Ronayne, a spokesman for the National Republican Senatorial Committee.
"I've always had confidence in the good judgment of voters to see through smoke screens," Ronayne said.
Thomas Mann, a veteran observer of Congress and politics at the Brookings Institution, said that Democratic Party officials went out of their way to find candidates, especially in Republican-leaning states, who could be competitive.
"They were very pragmatic this time. They recruited candidates who can win," Mann said.