I’ve seen this movie before, and I know how it ends. Republican candidates from presidential nominee Sen. John McCain (Ariz.) down to Congressional hopefuls have less than four weeks to figure out how to avert a repeat of 2006. Increasingly, it appears unlikely that they will.

[IMGCAP(1)]It’s obvious to all that the national landscape — and the presidential map — shifted dramatically in the Democrats’ favor during the financial crisis. Americans are more dissatisfied with the present and worried about the future, all of which helps Democratic presidential nominee Sen. Barack Obama (Ill.) and Democratic Congressional candidates.

Obama may not be comfortably over the crucial 50 percent mark in polls, but states that McCain hoped to compete in are moving out of reach, while more traditionally Republican states have come into play for Obama. McCain needs to change that dynamic quickly to have any chance of winning.

McCain still has a month to change the focus of the race, and Obama may have peaked too soon. But public concern about the economy isn’t likely to disappear over the next month no matter how much Republicans wish it would.

So far, there is no evidence that Democratic candidates are paying a price for the public’s sour mood, or that the election will be “anti-incumbent.” It is Republican candidates who are feeling the political pain.

The outlook in Senate races continues to deteriorate for Republicans, with Democratic gains at least in the high single digits increasingly likely. Where I once wrote in this space that Democrats had a chance of reaching 60 seats in 2010 (“For Democrats, Time to Pad Senate Majority and Think 60 Seats,” Feb. 12, 2007), I now can’t rule out 60 seats for this November.

Virginia and New Mexico are already gone, and Colorado, Alaska, New Hampshire and Oregon aren’t far behind. Add in North Carolina, and Democrats are plus-seven (and at 58 seats) without Minnesota or Mississippi, which are up for grabs.

Republicans can no longer count Kentucky as a lock, and if the Democrats spend significant sums of money against Sen. Saxby Chambliss (R) in Georgia, they might even have a chance to swipe that unlikely seat.

In the House of Representatives, Democratic prospects have gone from good to great.

The National Republican Congressional Committee has plenty of problems, but the most immediate one for its House candidates who are fighting for their political lives may well be the financial disadvantage those candidates face in outside spending.

The NRCC’s independent expenditure effort has so far bought TV time in two relatively inexpensive districts: for Rep. Phil English (R) in his northwest Pennsylvania district and in support of challenger John Gard in Wisconsin’s 8th district, currently represented by freshman Democratic Rep. Steve Kagen. Each buy, so far, is less than $150,000.

The Democratic Congressional Campaign Committee, on the other hand, has spent more than $400,000 in 15 districts, including in Republican Rep. Robin Hayes’ district in North Carolina, retiring Republican Rep. Deborah Pryce’s district in Ohio, retiring Republican Rep. Rick Renzi’s district in Arizona and Democratic Rep. Paul Kanjorski’s district in Pennsylvania.

Neither the NRCC nor Freedom’s Watch, which Democrats regularly warn their allies has replaced the NRCC as the “outside” group with the primary responsibility of spending money to elect Congressional Republicans, has spent a dime in any of those districts.

To this point, Freedom’s Watch has spent less than $2 million on House races while the DCCC’s spending has almost reached $15.5 million. Freedom’s Watch has so far spent more than $400,000 in only one district, New Jersey’s 7th.

The NRCC has scaled back advertising in Nevada’s 3rd district and New Mexico’s 1st district, and the campaign committee is going to have to make key decisions over the next few weeks about which candidates it will try to save and which it will allow to drown slowly.

With only about $22 million available to spend on races and many contests requiring a media buy of $1 million to make any impact, the NRCC simply cannot play in all the districts it needs to. And when Republican and GOP-leaning groups do spend their cash in the final weeks of the campaign, it may be too late to rescue Republican candidates who have picked up heavy negatives over the previous month.

This financial discrepancy is no surprise, but its impact is being felt at the worst time for Republicans.

While I recently increased my expectation of Democratic House gains to 10-20 seats, that range looks too low. Hardly any Democratic-held seats are at great risk — Democratic incumbents Kanjorski, Carol Shea-Porter (N.H.), Nick Lampson (Texas), Tim Mahoney (Fla.) and Don Cazayoux (La.), as well as an open seat in Alabama, are a few obvious exceptions — so the DCCC is almost entirely on offense.

Democrats are now likely to net at least 20 seats, with gains closer to 30 quite possible given the cycle’s dynamics, poll numbers we are seeing and the Democratic financial advantage. This is the kind of cycle when even one or two third-tier Democratic challengers will win, inflating the party’s net gain even further.

While Democratic gains both in the House and Senate could still grow or shrink, for Republicans, the end of this movie won’t be pretty, no matter the ultimate number.

We could see a new modern floor for House Republicans made in November, and it’s likely to be in the 170s, if not the upper 160s. Given the realignment of the Reagan years and the GOP’s advantages coming from the last redistricting, this is an incredibly low level.

Over on the Senate side, Republican numbers could fall further in two years, since more GOP seats than Democratic seats are again up in 2010.

Republicans appear to be heading into a disastrous election that will usher in a very bleak period for the party. A new generation of party leaders will have to figure out how to pick up the pieces and make their party relevant after November.

Stuart Rothenberg is editor of the Rothenberg Political Report.