A few months ago, only the most optimistic Democrats would have predicted a change in control of the Senate. Now the Democrats have a shot at doing just that, though the Republicans continue to hold most of the cards with the midterm election just a few days away.
The Democrats need to hold all of their seats and capture six GOP seats to regain control of the Senate. That means Democrats have the daunting task of winning in six of the seven states where GOP incumbents are seen as vulnerable: Pennsylvania, Ohio, Missouri, Montana, Virginia, Rhode Island and Tennessee. In addition, the Democrats will need to beat back strong GOP challenges to seats they hold in Maryland and New Jersey.
When the smoke clears, most analysts interviewed by CBSNews.com think the struggle for control of the Senate will be decided by the outcome of the races in Missouri, Virginia and Tennessee.
"What seems to be emerging as the three key bellwether states are Virginia, Tennessee and Missouri," said GOP pollster David Winston.
The party that wins two of these three races will most likely control the Senate in the 110th Congress.
Most political pundits believe that the Democrats will pick up four to seven Republican seats.
In four states — Pennsylvania, Ohio, Rhode Island and Montana — Republican incumbents are in trouble, according to the latest polls. But winning those four seats will give the Democrats just 49 votes. And that's why the Democrats need two of the three bellwether states.
The belief that the Democrats just might pull it off has been strengthened by the continued unpopularity of President Bush and the war in Iraq. Congressional Republicans have also been bedeviled by a series of scandals.
"Republicans are in trouble everywhere, all because of Bush's unpopularity," said Kenneth Warren, a professor of political science at Saint Louis University. President Bush's approval rating held steady at 34 percent in the.
History also seems to be working for the Democrats. While Mr. Bush was able to avoid traditional midterm losses in 2002, it appears the "six-year itch" is primed to bring about changes in Washington on the morning after Election Day.
"The second midterm is almost always a disaster," said Democratic pollster Harrison Hickman.
While they acknowledge the difficulty this election, Republicans believe they will remain ahead in the end. Brian Nick, a spokesman for the National Republican Senatorial Committee, said the GOP always knew the election would be tough, "but we feel very good about protecting out incumbents."
"This is going to be close in the end," said GOP pollster Winston. "Republicans are going to lose some seats and the question is whether Democrats can run the table."
The Big Three
The Show Me State has been known as one of the most reliable bellwether states. In presidential contests since 1904, Missourians have voted for the winner every time except for 1956. For that reason, it will be especially important to watch for the winner in this race between Republican incumbent Sen. Jim Talent and state auditor Claire McCaskill.
"Talent is in trouble because the political mood is pro-Democrat, anti-Bush," said Saint Louis University's Warren. "Issues in Missouri resonate nationally."
Of particular interest in Missouri has been the stem cell debate. In addition to their vote for senator, voters will be asked to vote on a referendum to allow more stem cell research. National attention focused on this race after an ad in favor of McCaskill featuring actoraired during the World Series.
That referendum and another that raises the state minimum wage both are likely to pass with wide margins, according to the latest polls. McCaskill's support for both measures will likely help her in the Senate race, according to Warren.
But McCaskill's prospects also may depend on whether she is able to connect with rural voters, who account for 47 percent of the electorate. After she lost the governor's race in 2004, she vowed to campaign more in the state's rural countryside.
However, Warren thinks this may be a risky strategy because so much time must be spent to reach voters who are spread out over 109 of the state's 114 counties. Also, Talent might be able to find an advantage by focusing his campaign on the urban areas to appeal to black voters who likely lean towards McCaskill. The latest polls show the race neck and neck with neither candidate pulling ahead.