ABC's Jonathan Karl reports from Washington:
It's been obscured by all the attention on the presidential race, but we may also be witnessing a congressional campaign worthy of the history books and with far-reaching implications for the next president.
Start with the House.
Democrats have the opportunity to do something no party has done since the Great Depression: Pick up more than 25 House seats in back-to-back elections. Democrats gained thirty seats in the last cycle. This time Democrats are predicting they'll pick up 20 to 25 seats. I think those are actually low-ball estimates. Just look at the playing field. The Cook Political Report lists 58 House races as competitive, of those 47 are vulnerable Republican seats; only 11 are now held by Democrats. And you can expect surprises, which, in a big Democratic year, are unlikely to favor Republicans.
Big sweeps like that can be enduring. After the elections of 1930 and 1932, Democrats controlled the House of Representatives for all but four of the next 62 years. The playing field for Senate races looks even worse for Republicans. There are a dozen competitive Senate races. All but one is for a seat now held by the Republicans. Democrats have a shot -- a long-shot, perhaps, but a shot -- of getting a 60-vote majority. That's enough to leave Republicans powerless to block legislation without at least some Democratic support.
Here's a humbling thought for Democrats if they win big on Tuesday: The last Democratic president to come to Washington with such big Democratic majorities in the House and Senate was Jimmy Carter. So can Democrats get 60 Senate seats for the first time since the 1970s? Here are three races to watch. Democrats will need to win at least one of these to get to 60. None of them are easy:
Kentucky. Sen. Mitch McConnell is the top Republican in the Senate and for years he's been the dominant political figure in Kentucky. Six years ago, he won re-election in the biggest landslide in the history of Kentucky Senate races. But the double-whammy of economic crisis and an unpopular president gives Democratic challenger Bruce Lunsford a chance. But this is a tough one: McConnell is a shrewd campaigner and he's helped by the fact that John McCain is expected to win big in Kentucky.
Mississippi. This race pits Republican Senator Roger Wicker, who was appointed to the seat after Trent Lott retired last December, against former Democratic governor Ronnie Musgrove. Musgrove is expected to get a big boost from what might be called the Obama Factor -- historically high African-American and youth turnout. This is a tough one for Democrats, too: The last non-incumbent Democrat to win a Senate seat from Mississippi was John Stennis in 1947.
Georgia. Senator Saxby Chambliss (R-GA) had been considered a safe bet, but the Obama Factor has Republicans in Georgia worried. If neither candidate gets 50 percent of the vote (and they may not because there is a Libertarian candidate), there will be runoff held in December. A run-off will likely be tougher for Democratic challenger Jim Martin, because he won't get the benefit of the Obama Factor.